diff --git a/.gitignore b/.gitignore
index b357a0c..0062c87 100644
--- a/.gitignore
+++ b/.gitignore
@@ -367,5 +367,10 @@ FodyWeavers.xsd
 */**/obj/Debug   
 */**/obj/Release   
 */Migrations
-/exercise.wwwapi/appsettings.json
-/exercise.wwwapi/appsettings.Development.json
+/exercise.webapi/appsettings.json
+/exercise.webapi/appsettings.Development.json
+
+*/**/appsettings.json
+*/**/appsettings.Development.json
+exercise.webapi/appsettings.json
+exercise.webapi/appsettings.Development.json
diff --git a/exercise.webapi/DTO/AuthorDto.cs b/exercise.webapi/DTO/AuthorDto.cs
new file mode 100644
index 0000000..edcc23e
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorDto.cs
@@ -0,0 +1,18 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class AuthorDto
+    {
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+
+        public AuthorDto(Author author)
+        {
+            FirstName = author.FirstName;
+            LastName = author.LastName;
+            Email = author.Email;
+        }
+    }
+}
diff --git a/exercise.webapi/DTO/AuthorResponseDto.cs b/exercise.webapi/DTO/AuthorResponseDto.cs
new file mode 100644
index 0000000..5754e83
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorResponseDto.cs
@@ -0,0 +1,19 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class AuthorResponseDto
+    {
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+        public List<BookPublisherDto> Books { get; set; }
+        public AuthorResponseDto(Author author)
+        {
+            FirstName = author.FirstName;
+            LastName = author.LastName;
+            Email = author.Email;
+            Books = author.Books.Select(book => new BookPublisherDto(book)).ToList();
+        }
+    }
+}
diff --git a/exercise.webapi/DTO/BookAuthorDto.cs b/exercise.webapi/DTO/BookAuthorDto.cs
new file mode 100644
index 0000000..75eb127
--- /dev/null
+++ b/exercise.webapi/DTO/BookAuthorDto.cs
@@ -0,0 +1,15 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookAuthorDto
+    {
+        public string Title { get; set; }
+        public string Author { get; set; }
+        public BookAuthorDto(string title, string author)
+        {
+            Title = title;
+            Author = author;
+        }
+    }
+}
diff --git a/exercise.webapi/DTO/BookDto.cs b/exercise.webapi/DTO/BookDto.cs
new file mode 100644
index 0000000..fabf609
--- /dev/null
+++ b/exercise.webapi/DTO/BookDto.cs
@@ -0,0 +1,19 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookDto
+    {
+        public string Title { get; set; }
+        public List<AuthorDto> Authors { get; set; }
+        public string Publisher { get; set; }
+
+        public BookDto(Book book)
+        {
+            Title = book.Title;
+            Authors = book.Authors.Select(a => new AuthorDto(a)).ToList();
+            Publisher = book.Publisher.Name;
+        }
+
+    }
+}
diff --git a/exercise.webapi/DTO/BookPublisherDto.cs b/exercise.webapi/DTO/BookPublisherDto.cs
new file mode 100644
index 0000000..36f9f4c
--- /dev/null
+++ b/exercise.webapi/DTO/BookPublisherDto.cs
@@ -0,0 +1,15 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookPublisherDto
+    {
+        public string Title { get; set; }
+        public string Publisher { get; set; }
+        public BookPublisherDto(Book book)
+        {
+            Title = book.Title;
+            Publisher = book.Publisher.Name;
+        }
+    }
+}
diff --git a/exercise.webapi/DTO/BookUpdateDto.cs b/exercise.webapi/DTO/BookUpdateDto.cs
new file mode 100644
index 0000000..8b1f6f1
--- /dev/null
+++ b/exercise.webapi/DTO/BookUpdateDto.cs
@@ -0,0 +1,9 @@
+namespace exercise.webapi.DTO
+{
+    public class BookUpdateDto
+    {
+        public string? Title { get; set; }
+        //public List<int>? AuthorIds { get; set; }
+        public int? PublisherId { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/CheckoutDto.cs b/exercise.webapi/DTO/CheckoutDto.cs
new file mode 100644
index 0000000..d5e1492
--- /dev/null
+++ b/exercise.webapi/DTO/CheckoutDto.cs
@@ -0,0 +1,18 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class CheckoutDto
+    {
+        public BookDto Book { get; set; }
+        public DateTime CheckoutDate { get; set; }
+        public DateTime DueDate { get; set; }
+
+        public CheckoutDto(Checkout checkout)
+        {
+            Book = new BookDto(checkout.Book);
+            CheckoutDate = checkout.CheckoutDate;
+            DueDate = checkout.DueDate;
+        }
+    }
+}
diff --git a/exercise.webapi/DTO/OverdueDto.cs b/exercise.webapi/DTO/OverdueDto.cs
new file mode 100644
index 0000000..f15f292
--- /dev/null
+++ b/exercise.webapi/DTO/OverdueDto.cs
@@ -0,0 +1,9 @@
+namespace exercise.webapi.DTO
+{
+    public class OverdueDto
+    {
+        public BookDto Book { get; set; }
+        public DateTime DueDate { get; set; }
+        public int DaysOverdue { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/UnavailableDto.cs b/exercise.webapi/DTO/UnavailableDto.cs
new file mode 100644
index 0000000..83178e9
--- /dev/null
+++ b/exercise.webapi/DTO/UnavailableDto.cs
@@ -0,0 +1,11 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class UnavailableDto
+    {
+        public BookDto Book { get; set; }
+        public DateTime AvailableBy { get; set; }
+        
+    }
+}
diff --git a/exercise.webapi/Data/DataContext.cs b/exercise.webapi/Data/DataContext.cs
index b6be7a9..46274eb 100644
--- a/exercise.webapi/Data/DataContext.cs
+++ b/exercise.webapi/Data/DataContext.cs
@@ -24,9 +24,15 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
             modelBuilder.Entity<Author>().HasData(seeder.Authors);
             modelBuilder.Entity<Book>().HasData(seeder.Books);
+            modelBuilder.Entity<Publisher>().HasData(seeder.Publishers);
+            modelBuilder.Entity<BookAuthor>().HasData(seeder.BookAuthors);
+            modelBuilder.Entity<Checkout>().HasData(seeder.Checkouts);
 
         }
         public DbSet<Author> Authors { get; set; }
         public DbSet<Book> Books { get; set; }
+        public DbSet<Publisher> Publishers { get; set; }
+        public DbSet<BookAuthor> BookAuthors { get; set; }
+        public DbSet<Checkout> Checkouts { get; set; }
     }
 }
diff --git a/exercise.webapi/Data/Seeder.cs b/exercise.webapi/Data/Seeder.cs
index 955e3c8..bccc61d 100644
--- a/exercise.webapi/Data/Seeder.cs
+++ b/exercise.webapi/Data/Seeder.cs
@@ -76,15 +76,34 @@ public class Seeder
             "Flowers",
             "Leopards"
         };
+        private List<string> _publisherStrings = new List<string>()
+        {
+            "Penguin",
+            "Random House",
+            "Harper Collins",
+            "Simon & Schuster",
+            "Macmillan",
+            "Hachette",
+            "Pearson",
+            "Scholastic",
+            "Bloomsbury",
+            "Oxford University Press"
+        };
 
         private List<Author> _authors = new List<Author>();
         private List<Book> _books = new List<Book>();
+        private List<Publisher> _publishers = new List<Publisher>();
+        private List<BookAuthor> _bookAuthors = new List<BookAuthor>();
+        private List<Checkout> _checkouts = new List<Checkout>();
+
 
         public Seeder()
         {
 
             Random authorRandom = new Random();
             Random bookRandom = new Random();
+            Random publisherRand = new Random();
+            //Random bookAuthorRandom = new Random();
 
 
 
@@ -104,14 +123,53 @@ public Seeder()
                 Book book = new Book();
                 book.Id = y;
                 book.Title = $"{_firstword[bookRandom.Next(_firstword.Count)]} {_secondword[bookRandom.Next(_secondword.Count)]} {_thirdword[bookRandom.Next(_thirdword.Count)]}";
-                book.AuthorId = _authors[authorRandom.Next(_authors.Count)].Id;
-                //book.Author = authors[book.AuthorId-1];
+                //book.Authors = new List<Author> { _authors[authorRandom.Next(_authors.Count)] };
+                book.PublisherId = publisherRand.Next(1, 11);
                 _books.Add(book);
             }
 
+            for(int z = 1; z < 11; z++)
+            {
+                Publisher publisher = new Publisher();
+                publisher.Id = z;
+                publisher.Name = _publisherStrings[z - 1];
+                _publishers.Add(publisher);
+            }
+
+            //Randomly assign authors to books, they should have at least one author, but can have more
+            foreach (var book in _books)
+            {
+                int numberOfAuthors = authorRandom.Next(1, 4);
+                for (int i = 0; i < numberOfAuthors; i++)
+                {
+                    BookAuthor bookAuthor = new BookAuthor();
+                    bookAuthor.Id = _bookAuthors.Count + 1;
+                    bookAuthor.AuthorId = authorRandom.Next(1, 250);
+                    bookAuthor.BookId = book.Id;
+                    _bookAuthors.Add(bookAuthor);
+                }
+            }
+
+
+            //Randomly check some books out. They should all be from various previous dates, some should be overdue, but not most.
+            Random checkoutRandom = new Random();
+            for (int i = 1; i < 100; i++)
+            {
+                Checkout checkout = new Checkout();
+                checkout.Id = i;
+                checkout.BookId = bookRandom.Next(1, 250);
+                checkout.CheckoutDate = DateTime.Now.AddDays(-checkoutRandom.Next(1, 365));
+                checkout.DueDate = checkout.CheckoutDate.AddDays(14);
+                checkout.IsReturned = checkoutRandom.Next(0, 2) == 1 ? true : false;
+                _checkouts.Add(checkout);
+            }
+
 
         }
         public List<Author> Authors { get { return _authors; } }
         public List<Book> Books { get { return _books; } }
+        public List<Publisher> Publishers { get { return _publishers; } }
+        public List<BookAuthor> BookAuthors { get { return _bookAuthors; } }
+        public List<Checkout> Checkouts { get { return _checkouts; } }
     }
 }
diff --git a/exercise.webapi/Endpoints/AuthorApi.cs b/exercise.webapi/Endpoints/AuthorApi.cs
new file mode 100644
index 0000000..35a9a8d
--- /dev/null
+++ b/exercise.webapi/Endpoints/AuthorApi.cs
@@ -0,0 +1,34 @@
+using exercise.webapi.DTO;
+using exercise.webapi.Repository;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class AuthorApi
+    {
+        public static void ConfigureAuthorsApi(this WebApplication app)
+        {
+            var authors = app.MapGroup("authors");
+            authors.MapGet("/{id}", GetAuthor);
+            authors.MapGet("/", GetAuthors);
+        }
+
+
+        private static async Task<IResult> GetAuthor(IAuthorRepository authorRepository,IPublisherRepository publisherRepository, int id)
+        {
+            var author = await authorRepository.GetAuthor(id);
+            if (author == null)
+            {
+                return Results.NotFound();
+            }
+
+            return TypedResults.Ok(new AuthorResponseDto(author));
+        }
+
+        private static async Task<IResult> GetAuthors(IAuthorRepository authorRepository)
+        {
+            var authors = await authorRepository.GetAuthors();
+            var authorDtos = authors.Select(author => new AuthorResponseDto(author));
+            return TypedResults.Ok(authorDtos);
+        }
+    }
+}
diff --git a/exercise.webapi/Endpoints/BookApi.cs b/exercise.webapi/Endpoints/BookApi.cs
index 6758215..7e98e22 100644
--- a/exercise.webapi/Endpoints/BookApi.cs
+++ b/exercise.webapi/Endpoints/BookApi.cs
@@ -1,5 +1,7 @@
-using exercise.webapi.Models;
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
 using exercise.webapi.Repository;
+using Microsoft.AspNetCore.Mvc;
 using static System.Reflection.Metadata.BlobBuilder;
 
 namespace exercise.webapi.Endpoints
@@ -9,12 +11,133 @@ public static class BookApi
         public static void ConfigureBooksApi(this WebApplication app)
         {
             app.MapGet("/books", GetBooks);
+            app.MapGet("/books/{id}", GetBook);
+            app.MapPut("/books/{id}", UpdateBook);
+            app.MapDelete("/books/{id}", DeleteBook);
+            app.MapPost("/books", AddBook);
+            app.MapPost("/books/{id}/authors/{authorId}", AddAuthorToBook);
+            app.MapDelete("/books/{id}/authors/{authorId}", RemoveAuthorFromBook);
+            //Get unavailable books, we might use queryparameters and the checkoutrepository
+            app.MapGet("/books/unavailable", GetUnavailableBooks);
         }
 
         private static async Task<IResult> GetBooks(IBookRepository bookRepository)
         {
             var books = await bookRepository.GetAllBooks();
-            return TypedResults.Ok(books);
+            var bookDtos = books.Select(book => new BookDto(book));
+            return TypedResults.Ok(bookDtos);
+        }
+
+        private static async Task<IResult> GetBook(IBookRepository bookRepository, int id)
+        {
+            var book = await bookRepository.GetBook(id);
+            if (book == null)
+            {
+                return Results.NotFound();
+            }
+            return TypedResults.Ok(new BookDto(book));
+        }
+
+        private static async Task<IResult> UpdateBook(IBookRepository bookRepository, int id, BookUpdateDto updates)
+        {
+            var book = await bookRepository.GetBook(id);
+            if (book == null)
+            {
+                return Results.NotFound();
+            }
+
+            //book.AuthorId = updates.AuthorId;
+            if (!string.IsNullOrWhiteSpace(updates.Title))
+                book.Title = updates.Title;
+            if (updates.PublisherId != null)
+                book.PublisherId = (int)updates.PublisherId;
+
+            await bookRepository.UpdateBook(book);
+            Book updatedBook = await bookRepository.GetBook(id);
+            return TypedResults.Ok(new BookDto(updatedBook));
+        }
+
+        private static async Task<IResult> DeleteBook(IBookRepository bookRepository, int id)
+        {
+            var success = await bookRepository.DeleteBook(id);
+            if (!success)
+            {
+                return TypedResults.NotFound();
+            }
+            return TypedResults.Ok("Successfully deleted!");
+        }
+
+        [ProducesResponseType(StatusCodes.Status201Created)]
+        [ProducesResponseType(StatusCodes.Status400BadRequest)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        private static async Task<IResult> AddBook(IBookRepository bookRepository, IAuthorRepository authorRepository, IPublisherRepository publisherRepository, BookUpdateDto bookUpdateDto)
+        {
+            if (bookUpdateDto.PublisherId == null)
+            {
+                return TypedResults.BadRequest("PublisherId is required");
+            }
+            var publisher = await publisherRepository.GetPublisher((int)bookUpdateDto.PublisherId);
+            if (publisher == null)
+            {
+                return TypedResults.NotFound();
+            }
+            var book = new Book
+            {
+                Title = bookUpdateDto.Title,
+                PublisherId = (int)bookUpdateDto.PublisherId
+            };
+            await bookRepository.AddBook(book);
+            return TypedResults.Created($"https://localhost/7054/books/{book.Id}", new BookDto(book));
+        }
+
+        private static async Task<IResult> AddAuthorToBook(IBookRepository bookRepository, IAuthorRepository authorRepository, IBookAuthorRepository bookAuthorRepository, int id, int authorId)
+        {
+            var book = await bookRepository.GetBook(id);
+            var author = await authorRepository.GetAuthor(authorId);
+            if (book == null || author == null)
+            {
+                return TypedResults.NotFound();
+            }
+            var BookAuthor = new BookAuthor
+            {
+                BookId = book.Id,
+                AuthorId = author.Id
+            };
+
+            bookAuthorRepository.AddBookAuthor(BookAuthor);
+            return TypedResults.Ok(new BookAuthorDto(book.Title, author.FirstName + author.LastName));
+        }
+
+        private static async Task<IResult> RemoveAuthorFromBook(IBookRepository bookRepository, IAuthorRepository authorRepository, IBookAuthorRepository bookAuthorRepository, int id, int authorId)
+        {
+            var book = await bookRepository.GetBook(id);
+            var author = await authorRepository.GetAuthor(authorId);
+            if (book == null || author == null)
+            {
+                return TypedResults.NotFound();
+            }
+            var bookAuthor = book.BookAuthors.FirstOrDefault(ba => ba.AuthorId == author.Id);
+            if (bookAuthor == null)
+            {
+                return TypedResults.NotFound();
+            }
+            bookAuthorRepository.DeleteBookAuthor(bookAuthor.Id);
+            return TypedResults.Ok();
+        }
+
+        private static async Task<IResult> GetUnavailableBooks(ICheckoutRepository checkoutRepository, IBookRepository bookRepository)
+        {
+            var checkouts = await checkoutRepository.GetAllCheckouts();
+            var unavailableBooks = checkouts
+                .Where(c => !c.IsReturned)
+                .Select(c => new UnavailableDto
+                {
+                    Book = new BookDto(c.Book),
+                    AvailableBy = c.DueDate,
+                })
+                .ToList();
+
+            return TypedResults.Ok(unavailableBooks);
         }
     }
 }
diff --git a/exercise.webapi/Endpoints/CheckoutApi.cs b/exercise.webapi/Endpoints/CheckoutApi.cs
new file mode 100644
index 0000000..d0cd4ef
--- /dev/null
+++ b/exercise.webapi/Endpoints/CheckoutApi.cs
@@ -0,0 +1,52 @@
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
+using exercise.webapi.Repository;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class CheckoutApi
+    {
+        public static void ConfigureCheckoutApi(this WebApplication app)
+        {
+            var checkout = app.MapGroup("checkout");
+            checkout.MapPost("/{bookId}", Checkout);
+            checkout.MapGet("/overdue", GetOverdueBooks);
+        }
+
+        private static async Task<IResult> Checkout(ICheckoutRepository checkoutRepository,IBookRepository bookRepository, int bookId)
+        {
+            bool checkedOut = await checkoutRepository.IsCheckedOut(bookId);
+            if (checkedOut)
+            {
+                return TypedResults.Ok("Book is unavailable");
+            }
+            Book book = await bookRepository.GetBook(bookId);
+            Checkout checkout = new Checkout
+            {
+                BookId = bookId,
+                DueDate = DateTime.Now.AddDays(14),
+                IsReturned = false,
+                CheckoutDate = DateTime.Now,
+                Book = book
+            };
+            await checkoutRepository.AddCheckout(checkout);
+            return TypedResults.Ok(new CheckoutDto(checkout));
+        }
+
+
+        public static async Task<IResult> GetOverdueBooks(IBookRepository bookRepository, ICheckoutRepository checkoutRepository)
+        {
+            var checkouts = await checkoutRepository.GetAllCheckouts();
+            var overdue = checkouts.Where(c => c.DueDate < DateTime.Now && !c.IsReturned).OrderBy(c => c.DueDate);
+            var overdueBooks = overdue.Select(c => new OverdueDto
+            {
+                Book = new BookDto(c.Book),
+                DueDate = c.DueDate,
+                DaysOverdue = (DateTime.Now - c.DueDate).Days
+            });
+            return TypedResults.Ok(overdueBooks);
+        }
+
+
+    }
+}
diff --git a/exercise.webapi/Endpoints/PublisherApi.cs b/exercise.webapi/Endpoints/PublisherApi.cs
new file mode 100644
index 0000000..ed0ff79
--- /dev/null
+++ b/exercise.webapi/Endpoints/PublisherApi.cs
@@ -0,0 +1,33 @@
+using exercise.webapi.Repository;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class PublisherApi
+    {
+        public static void ConfigurePublishersApi(this WebApplication app)
+        {
+            var publishers = app.MapGroup("publishers");
+            publishers.MapGet("/{id}", GetPublisher);
+            publishers.MapGet("/", GetPublishers);
+        }
+
+
+        private static async Task<IResult> GetPublisher(IPublisherRepository publisherRepository, int id)
+        {
+            var publisher = await publisherRepository.GetPublisher(id);
+            if (publisher == null)
+            {
+                return Results.NotFound();
+            }
+            return TypedResults.Ok(publisher.Name);
+        }
+
+
+        private static async Task<IResult> GetPublishers(IPublisherRepository publisherRepository)
+        {
+            var publishers = await publisherRepository.GetPublishers();
+            var publisherNames = publishers.Select(publisher => (publisher.Name));
+            return TypedResults.Ok(publisherNames);
+        }
+    }
+}
diff --git a/exercise.webapi/Models/Author.cs b/exercise.webapi/Models/Author.cs
index 9f47878..7199a52 100644
--- a/exercise.webapi/Models/Author.cs
+++ b/exercise.webapi/Models/Author.cs
@@ -8,8 +8,7 @@ public class Author
         public string FirstName { get; set; }
         public string LastName { get; set; }
         public string Email { get; set; }
-
-        [JsonIgnore] // Todo: replace this with DTO approach
+        public List<BookAuthor> BookAuthors { get; set; } = new List<BookAuthor>();
         public ICollection<Book> Books { get; set; } = new List<Book>();
     }
 }
diff --git a/exercise.webapi/Models/Book.cs b/exercise.webapi/Models/Book.cs
index 9534929..fb76e97 100644
--- a/exercise.webapi/Models/Book.cs
+++ b/exercise.webapi/Models/Book.cs
@@ -6,8 +6,9 @@ public class Book
     {
         public int Id { get; set; }
         public string Title { get; set; }
-        
-        public int AuthorId { get; set; }
-        public Author Author { get; set; }
+        public int PublisherId { get; set; }
+        public List<BookAuthor> BookAuthors { get; set; }
+        public List<Author> Authors { get; set; }
+        public Publisher Publisher { get; set; }
     }
 }
diff --git a/exercise.webapi/Models/BookAuthor.cs b/exercise.webapi/Models/BookAuthor.cs
new file mode 100644
index 0000000..66eae81
--- /dev/null
+++ b/exercise.webapi/Models/BookAuthor.cs
@@ -0,0 +1,11 @@
+namespace exercise.webapi.Models
+{
+    public class BookAuthor
+    {
+        public int Id { get; set; }
+        public int BookId { get; set; }
+        public int AuthorId { get; set; }
+        public Book Book { get; set; }
+        public Author Author { get; set; }
+    }
+}
diff --git a/exercise.webapi/Models/Checkout.cs b/exercise.webapi/Models/Checkout.cs
new file mode 100644
index 0000000..4503c17
--- /dev/null
+++ b/exercise.webapi/Models/Checkout.cs
@@ -0,0 +1,14 @@
+namespace exercise.webapi.Models
+{
+    public class Checkout
+    {
+        public int Id { get; set; }
+        public int BookId { get; set; }
+        public DateTime CheckoutDate { get; set; }
+        public bool IsReturned { get; set; }
+        public DateTime DueDate { get; set; }
+        public Book Book { get; set; }
+
+    }
+  
+}
diff --git a/exercise.webapi/Models/Publisher.cs b/exercise.webapi/Models/Publisher.cs
new file mode 100644
index 0000000..98a7276
--- /dev/null
+++ b/exercise.webapi/Models/Publisher.cs
@@ -0,0 +1,9 @@
+namespace exercise.webapi.Models
+{
+    public class Publisher
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+        public ICollection<Book> Books { get; set; } = new List<Book>();
+    }
+}
diff --git a/exercise.webapi/Program.cs b/exercise.webapi/Program.cs
index 43dec56..c097285 100644
--- a/exercise.webapi/Program.cs
+++ b/exercise.webapi/Program.cs
@@ -1,3 +1,4 @@
+using System.Diagnostics;
 using exercise.webapi.Data;
 using exercise.webapi.Endpoints;
 using exercise.webapi.Repository;
@@ -11,7 +12,15 @@
 builder.Services.AddSwaggerGen();
 builder.Services.AddDbContext<DataContext>(opt => opt.UseInMemoryDatabase("Library"));
 builder.Services.AddScoped<IBookRepository, BookRepository>();
+builder.Services.AddScoped<IAuthorRepository, AuthorRepository>();
+builder.Services.AddScoped<IPublisherRepository, PublisherRepository>();
+builder.Services.AddScoped<IBookAuthorRepository, BookAuthorRepository>();
+builder.Services.AddScoped<ICheckoutRepository, CheckoutRepository>();
+builder.Services.AddDbContext<DataContext>(options => {
+    //options.UseNpgsql(builder.Configuration.GetConnectionString("DefaultConnectionString"));
+    options.LogTo(message => Debug.WriteLine(message));
 
+});
 var app = builder.Build();
 
 using (var dbContext = new DataContext(new DbContextOptions<DataContext>()))
@@ -29,4 +38,7 @@
 
 app.UseHttpsRedirection();
 app.ConfigureBooksApi();
+app.ConfigureAuthorsApi();
+app.ConfigurePublishersApi();
+app.ConfigureCheckoutApi();
 app.Run();
diff --git a/exercise.webapi/Repository/AuthorRepository.cs b/exercise.webapi/Repository/AuthorRepository.cs
new file mode 100644
index 0000000..8a222ea
--- /dev/null
+++ b/exercise.webapi/Repository/AuthorRepository.cs
@@ -0,0 +1,40 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace exercise.webapi.Repository
+{
+    public class AuthorRepository: IAuthorRepository
+    {
+        DataContext _db;
+        public AuthorRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+
+        public async Task<Author> GetAuthor(int id)
+        {
+            var author =  await _db.Authors
+                .Include(a => a.BookAuthors)
+                .ThenInclude(ba => ba.Book)
+                .ThenInclude(b => b.Publisher)
+                .FirstOrDefaultAsync(a => a.Id == id);
+            author.Books = author.BookAuthors.Select(ba => ba.Book).ToList();
+            return author;
+        }
+
+
+
+        public async Task<IEnumerable<Author>> GetAuthors()
+        {
+            var authors =  await _db.Authors
+                .Include(a => a.BookAuthors)
+                .ThenInclude(ba => ba.Book)
+                .ThenInclude(b => b.Publisher)
+                .ToListAsync();
+            authors.ForEach(a => a.Books = a.BookAuthors.Select(ba => ba.Book).ToList());
+            return authors;
+        }
+    }
+}
diff --git a/exercise.webapi/Repository/BookAuthorRepository.cs b/exercise.webapi/Repository/BookAuthorRepository.cs
new file mode 100644
index 0000000..1d3efae
--- /dev/null
+++ b/exercise.webapi/Repository/BookAuthorRepository.cs
@@ -0,0 +1,32 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public class BookAuthorRepository : IBookAuthorRepository
+    {
+        DataContext _db;
+        public BookAuthorRepository(DataContext db)
+        {
+            _db = db;
+        }
+        public async Task<BookAuthor> AddBookAuthor(BookAuthor bookAuthor)
+        {
+            await _db.BookAuthors.AddAsync(bookAuthor);
+            await _db.SaveChangesAsync();
+            return bookAuthor;
+        }
+
+        public async Task<bool> DeleteBookAuthor(int id)
+        {
+            var bookAuthor = await _db.BookAuthors.FindAsync(id);
+            if (bookAuthor == null)
+            {
+                return false;
+            }
+            _db.BookAuthors.Remove(bookAuthor);
+            await _db.SaveChangesAsync();
+            return true;
+        }
+    }
+}
diff --git a/exercise.webapi/Repository/BookRepository.cs b/exercise.webapi/Repository/BookRepository.cs
index 1f5e64a..0fcf064 100644
--- a/exercise.webapi/Repository/BookRepository.cs
+++ b/exercise.webapi/Repository/BookRepository.cs
@@ -4,10 +4,10 @@
 
 namespace exercise.webapi.Repository
 {
-    public class BookRepository: IBookRepository
+    public class BookRepository : IBookRepository
     {
         DataContext _db;
-        
+
         public BookRepository(DataContext db)
         {
             _db = db;
@@ -15,8 +15,49 @@ public BookRepository(DataContext db)
 
         public async Task<IEnumerable<Book>> GetAllBooks()
         {
-            return await _db.Books.Include(b => b.Author).ToListAsync();
+            var books = await _db.Books
+                .Include(b => b.BookAuthors)
+                .ThenInclude(ba => ba.Author)
+                .Include(b => b.Publisher)
+                .ToListAsync();
+            books.ForEach(b => b.Authors = b.BookAuthors.Select(ba => ba.Author).ToList());
+            return books;
+        }
+
+        public async Task<Book> GetBook(int id)
+        {
+            var book = await _db.Books
+                .Include(b => b.BookAuthors)
+                .ThenInclude(ba => ba.Author)
+                .Include(b => b.Publisher)
+                .FirstOrDefaultAsync(b => b.Id == id);
+           book.Authors = book.BookAuthors.Select(ba => ba.Author).ToList();
+            return book;
+        }
+   
+        public async Task<Book> UpdateBook(Book book)
+        {
+            _db.Books.Update(book);
+            await _db.SaveChangesAsync();
+            return book;
+        }
 
+        public async Task<bool> DeleteBook(int id)
+        {
+            var book = await _db.Books.FindAsync(id);
+            if (book == null)
+            {
+                return false;
+            }
+            _db.Books.Remove(book);
+            await _db.SaveChangesAsync();
+            return true;
+        }
+        public async Task<Book> AddBook(Book book)
+        {
+            await _db.Books.AddAsync(book);
+            await _db.SaveChangesAsync();
+            return book;
         }
     }
 }
diff --git a/exercise.webapi/Repository/CheckoutRepository.cs b/exercise.webapi/Repository/CheckoutRepository.cs
new file mode 100644
index 0000000..764d69e
--- /dev/null
+++ b/exercise.webapi/Repository/CheckoutRepository.cs
@@ -0,0 +1,68 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace exercise.webapi.Repository
+{
+    public class CheckoutRepository : ICheckoutRepository
+    {
+        DataContext _db;
+        public CheckoutRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+
+        public async Task<Checkout> GetCheckout(int id)
+        {
+            return await _db.Checkouts
+                .Include(c => c.Book)
+                    .ThenInclude(b => b.BookAuthors)
+                        .ThenInclude(ba => ba.Author)
+                .Include(c => c.Book)
+                    .ThenInclude(b => b.Publisher)
+                .FirstOrDefaultAsync(c => c.Id == id);
+        }
+
+
+        public async Task<Checkout> AddCheckout(Checkout checkout)
+        {
+            await _db.Checkouts.AddAsync(checkout);
+            await _db.SaveChangesAsync();
+            return checkout;
+        }
+
+        public async Task<IEnumerable<Checkout>> GetAllCheckouts()
+        {
+            var checkouts =  await _db.Checkouts
+                .Include(c => c.Book)
+                    .ThenInclude(b => b.BookAuthors)
+                        .ThenInclude(ba => ba.Author)
+                .Include(c => c.Book)
+                    .ThenInclude(b => b.Publisher).ToListAsync();
+            checkouts.ForEach(c => c.Book.Authors = c.Book.BookAuthors.Select(ba => ba.Author).ToList());
+            return checkouts;
+        }
+
+        public async Task<bool> DeleteCheckout(int id)
+        {
+            throw new NotImplementedException();
+        }
+
+        public async Task<bool> UpdateCheckout(Checkout checkout)
+        {
+            throw new NotImplementedException();
+
+        }
+
+        public async Task<bool> IsCheckedOut(int bookId)
+        {
+            var checkout =  await _db.Checkouts.FirstOrDefaultAsync(c => c.BookId == bookId && !c.IsReturned);
+            if (checkout == null)
+            {
+                return false;
+            }
+            return true;
+        }
+    }
+}
diff --git a/exercise.webapi/Repository/IAuthorRepository.cs b/exercise.webapi/Repository/IAuthorRepository.cs
new file mode 100644
index 0000000..c80139e
--- /dev/null
+++ b/exercise.webapi/Repository/IAuthorRepository.cs
@@ -0,0 +1,10 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface IAuthorRepository
+    {
+        public Task<Author> GetAuthor(int id);
+        public Task<IEnumerable<Author>> GetAuthors();
+    }
+}
diff --git a/exercise.webapi/Repository/IBookAuthorRepository.cs b/exercise.webapi/Repository/IBookAuthorRepository.cs
new file mode 100644
index 0000000..1df8108
--- /dev/null
+++ b/exercise.webapi/Repository/IBookAuthorRepository.cs
@@ -0,0 +1,10 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface IBookAuthorRepository
+    {
+        public Task<bool> DeleteBookAuthor(int id);
+        public Task<BookAuthor> AddBookAuthor(BookAuthor bookAuthor);
+    }
+}
diff --git a/exercise.webapi/Repository/IBookRepository.cs b/exercise.webapi/Repository/IBookRepository.cs
index f860016..7146fcf 100644
--- a/exercise.webapi/Repository/IBookRepository.cs
+++ b/exercise.webapi/Repository/IBookRepository.cs
@@ -5,5 +5,10 @@ namespace exercise.webapi.Repository
     public interface IBookRepository
     {
         public Task<IEnumerable<Book>> GetAllBooks();
+        public Task<Book> GetBook(int id);
+
+        public Task<Book> UpdateBook(Book book);
+        public Task<bool> DeleteBook(int id);
+        public Task<Book> AddBook(Book book);
     }
 }
diff --git a/exercise.webapi/Repository/ICheckoutRepository.cs b/exercise.webapi/Repository/ICheckoutRepository.cs
new file mode 100644
index 0000000..fc697d0
--- /dev/null
+++ b/exercise.webapi/Repository/ICheckoutRepository.cs
@@ -0,0 +1,15 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface ICheckoutRepository
+    {
+        public Task<IEnumerable<Checkout>> GetAllCheckouts();
+        public Task<Checkout> GetCheckout(int id);
+        public Task<Checkout> AddCheckout(Checkout checkout);
+        public Task<bool> DeleteCheckout(int id);
+        public Task<bool> UpdateCheckout(Checkout checkout);
+        public Task<bool> IsCheckedOut(int bookId);
+
+    }
+}
diff --git a/exercise.webapi/Repository/IPublisherRepository.cs b/exercise.webapi/Repository/IPublisherRepository.cs
new file mode 100644
index 0000000..e44fc0c
--- /dev/null
+++ b/exercise.webapi/Repository/IPublisherRepository.cs
@@ -0,0 +1,10 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface IPublisherRepository
+    {
+        public Task<Publisher> GetPublisher(int id);
+        public Task<IEnumerable<Publisher>> GetPublishers();
+    }
+}
diff --git a/exercise.webapi/Repository/PublisherRepository.cs b/exercise.webapi/Repository/PublisherRepository.cs
new file mode 100644
index 0000000..ee9f862
--- /dev/null
+++ b/exercise.webapi/Repository/PublisherRepository.cs
@@ -0,0 +1,25 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+using Microsoft.EntityFrameworkCore;
+
+namespace exercise.webapi.Repository
+{
+    public class PublisherRepository : IPublisherRepository
+    {
+        DataContext _db;
+        public PublisherRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+        public async Task<Publisher> GetPublisher(int id)
+        {
+            return await _db.Publishers.Include(p => p.Books).FirstOrDefaultAsync(p => p.Id == id);
+        }
+
+        public async Task<IEnumerable<Publisher>> GetPublishers()
+        {
+            return await _db.Publishers.Include(p => p.Books).ToListAsync();
+        }
+    }
+}
diff --git a/exercise.webapi/appsettings.json b/exercise.webapi/appsettings.json
index 63d13d3..860039d 100644
--- a/exercise.webapi/appsettings.json
+++ b/exercise.webapi/appsettings.json
@@ -7,8 +7,8 @@
   },
   "AllowedHosts": "*",
 
-  "ConnectionStrings": {
-    "DefaultConnectionString": "Host=ep-winter-silence-a8e5oju7.eastus2.azure.neon.tech; Database=neondb; Username=neondb_owner; Password=npg_nBmYdDo0Lr3z;"
+    "ConnectionStrings": {
+        "DefaultConnectionString": "Host=ep-morning-rice-a926sulq.gwc.azure.neon.tech; Database=introexercise; Username=neondb_owner; Password=npg_NUJ2IPBDjs7V;"
 
-  }
+    }
 } 
\ No newline at end of file