diff --git a/exercise.webapi/DTO/AuthorGetDTO.cs b/exercise.webapi/DTO/AuthorGetDTO.cs
new file mode 100644
index 0000000..a3819ed
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorGetDTO.cs
@@ -0,0 +1,14 @@
+using System.Text.Json.Serialization;
+
+namespace exercise.webapi.DTO
+{
+    public class AuthorGetDTO
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+        public List<BookGetDTO>? Books { get; set; }
+        public List<PublisherGetDTO>? Publishers { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/AuthorPostDTO.cs b/exercise.webapi/DTO/AuthorPostDTO.cs
new file mode 100644
index 0000000..12d8a62
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorPostDTO.cs
@@ -0,0 +1,11 @@
+namespace exercise.webapi.DTO
+{
+    public class AuthorPostDTO
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+        public List<BookPostDTO> Books { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/AuthorPutDTO.cs b/exercise.webapi/DTO/AuthorPutDTO.cs
new file mode 100644
index 0000000..353f62e
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorPutDTO.cs
@@ -0,0 +1,10 @@
+namespace exercise.webapi.DTO
+{
+    public class AuthorPutDTO
+    {
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+        public List<BookPutDTO> Books { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/AuthorReponseDTO.cs b/exercise.webapi/DTO/AuthorReponseDTO.cs
new file mode 100644
index 0000000..8e1a1f1
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorReponseDTO.cs
@@ -0,0 +1,18 @@
+using exercise.webapi.Models;
+using System.Text.Json.Serialization;
+
+namespace exercise.webapi.DTO
+{
+    public class AuthorReponseDTO
+    {
+        public DateTime When { get; set; } = DateTime.Now;
+        public string Status { get; set; } = "";
+
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+
+        public List<BookResponseDTO> Books { get; set; } = new List<BookResponseDTO>();
+    }
+}
diff --git a/exercise.webapi/DTO/BookGetDTO.cs b/exercise.webapi/DTO/BookGetDTO.cs
new file mode 100644
index 0000000..29511e2
--- /dev/null
+++ b/exercise.webapi/DTO/BookGetDTO.cs
@@ -0,0 +1,19 @@
+using System.Text.Json.Serialization;
+
+namespace exercise.webapi.DTO
+{
+    public class BookGetDTO
+    {
+        public int Id { get; set; }
+        public string Title { get; set; }
+
+        [JsonIgnore]
+        public int AuthorId { get; set; }
+        public AuthorGetDTO? Author { get; set; }
+
+        [JsonIgnore]
+        public int PublisherId { get; set; }
+
+        public PublisherGetDTO? Publisher { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookPostDTO.cs b/exercise.webapi/DTO/BookPostDTO.cs
new file mode 100644
index 0000000..63a3465
--- /dev/null
+++ b/exercise.webapi/DTO/BookPostDTO.cs
@@ -0,0 +1,11 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookPostDTO
+    {
+        public string Title { get; set; }
+        public int AuthorId { get; set; }
+        public int PublisherId { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookPutDTO.cs b/exercise.webapi/DTO/BookPutDTO.cs
new file mode 100644
index 0000000..bb768cd
--- /dev/null
+++ b/exercise.webapi/DTO/BookPutDTO.cs
@@ -0,0 +1,10 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookPutDTO
+    {
+        public int AuthorId { get; set; }
+        public int PublisherId { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookResponseDTO.cs b/exercise.webapi/DTO/BookResponseDTO.cs
new file mode 100644
index 0000000..c307026
--- /dev/null
+++ b/exercise.webapi/DTO/BookResponseDTO.cs
@@ -0,0 +1,7 @@
+namespace exercise.webapi.DTO
+{
+    public class BookResponseDTO
+    {
+        public string Title { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/PublisherGetDTO.cs b/exercise.webapi/DTO/PublisherGetDTO.cs
new file mode 100644
index 0000000..b268b1b
--- /dev/null
+++ b/exercise.webapi/DTO/PublisherGetDTO.cs
@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+
+namespace exercise.webapi.DTO
+{
+    public class PublisherGetDTO
+    {
+        public int Id { get; set; }
+        public string Name { get; set; }
+
+        public List<BookGetDTO>? Books { get; set; }
+    }
+}
diff --git a/exercise.webapi/Data/DataContext.cs b/exercise.webapi/Data/DataContext.cs
index b6be7a9..3b3828f 100644
--- a/exercise.webapi/Data/DataContext.cs
+++ b/exercise.webapi/Data/DataContext.cs
@@ -24,9 +24,11 @@ protected override void OnModelCreating(ModelBuilder modelBuilder)
 
             modelBuilder.Entity<Author>().HasData(seeder.Authors);
             modelBuilder.Entity<Book>().HasData(seeder.Books);
+            modelBuilder.Entity<Publisher>().HasData(seeder.Publishers);
 
         }
         public DbSet<Author> Authors { get; set; }
         public DbSet<Book> Books { get; set; }
+        public DbSet<Publisher> Publishers { get; set; }
     }
 }
diff --git a/exercise.webapi/Data/Seeder.cs b/exercise.webapi/Data/Seeder.cs
index 955e3c8..7405ba4 100644
--- a/exercise.webapi/Data/Seeder.cs
+++ b/exercise.webapi/Data/Seeder.cs
@@ -1,4 +1,5 @@
 using exercise.webapi.Models;
+using Microsoft.EntityFrameworkCore;
 
 namespace exercise.webapi.Data
 {
@@ -6,112 +7,97 @@ public class Seeder
     {
         private List<string> _firstnames = new List<string>()
         {
-            "Audrey",
-            "Donald",
-            "Elvis",
-            "Barack",
-            "Oprah",
-            "Jimi",
-            "Mick",
-            "Kate",
-            "Charles",
-            "Kate"
+            "Audrey", "Donald", "Elvis", "Barack", "Oprah",
+            "Jimi", "Mick", "Kate", "Charles", "Kate"
         };
+
         private List<string> _lastnames = new List<string>()
         {
-            "Hepburn",
-            "Trump",
-            "Presley",
-            "Obama",
-            "Winfrey",
-            "Hendrix",
-            "Jagger",
-            "Winslet",
-            "Windsor",
-            "Middleton"
-
+            "Hepburn", "Trump", "Presley", "Obama", "Winfrey",
+            "Hendrix", "Jagger", "Winslet", "Windsor", "Middleton"
         };
+
         private List<string> _domain = new List<string>()
         {
-            "bbc.co.uk",
-            "google.com",
-            "theworld.ca",
-            "something.com",
-            "tesla.com",
-            "nasa.org.us",
-            "gov.us",
-            "gov.gr",
-            "gov.nl",
-            "gov.ru"
+            "bbc.co.uk", "google.com", "theworld.ca", "something.com",
+            "tesla.com", "nasa.org.us", "gov.us", "gov.gr", "gov.nl", "gov.ru"
         };
+
         private List<string> _firstword = new List<string>()
         {
-            "The",
-            "Two",
-            "Several",
-            "Fifteen",
-            "A bunch of",
-            "An army of",
-            "A herd of"
-
-
+            "The", "Two", "Several", "Fifteen", "A bunch of", "An army of", "A herd of"
         };
+
         private List<string> _secondword = new List<string>()
         {
-            "Orange",
-            "Purple",
-            "Large",
-            "Microscopic",
-            "Green",
-            "Transparent",
-            "Rose Smelling",
-            "Bitter"
+            "Orange", "Purple", "Large", "Microscopic", "Green", "Transparent", "Rose Smelling", "Bitter"
         };
+
         private List<string> _thirdword = new List<string>()
         {
-            "Buildings",
-            "Cars",
-            "Planets",
-            "Houses",
-            "Flowers",
-            "Leopards"
+            "Buildings", "Cars", "Planets", "Houses", "Flowers", "Leopards"
+        };
+
+        private List<string> _publisherNames = new List<string>()
+        {
+            "Penguin Random House", "Simon & Schuster", "HarperCollins",
+            "Hachette Livre", "Scholastic", "Macmillan Publishers",
+            "Bloomsbury Publishing", "DK Publishing", "Wiley", "McGraw-Hill Education"
         };
 
         private List<Author> _authors = new List<Author>();
         private List<Book> _books = new List<Book>();
+        private List<Publisher> _publishers = new List<Publisher>();
 
         public Seeder()
         {
+            Random random = new Random();
 
-            Random authorRandom = new Random();
-            Random bookRandom = new Random();
-
-
-
-            for (int x = 1; x < 250; x++)
+            // Create Authors
+            for (int x = 1; x <= 50; x++)
             {
-                Author author = new Author();
-                author.Id = x;
-                author.FirstName = _firstnames[authorRandom.Next(_firstnames.Count)];
-                author.LastName = _lastnames[authorRandom.Next(_lastnames.Count)];
-                author.Email = $"{author.FirstName}.{author.LastName}@{_domain[authorRandom.Next(_domain.Count)]}".ToLower();
+                Author author = new Author
+                {
+                    Id = x,
+                    FirstName = _firstnames[random.Next(_firstnames.Count)],
+                    LastName = _lastnames[random.Next(_lastnames.Count)],
+                    Email = $"{_firstnames[random.Next(_firstnames.Count)]}.{_lastnames[random.Next(_lastnames.Count)]}@{_domain[random.Next(_domain.Count)]}".ToLower()
+                };
                 _authors.Add(author);
             }
 
+            // Create Publishers
+            for (int x = 1; x <= _publisherNames.Count; x++)
+            {
+                Publisher publisher = new Publisher
+                {
+                    Id = x,
+                    Name = _publisherNames[x - 1]
+                };
+                _publishers.Add(publisher);
+            }
 
-            for (int y = 1; y < 250; y++)
+            // Create Books
+            for (int x = 1; x <= 50; x++)
             {
-                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];
+                Author randomAuthor = _authors[random.Next(_authors.Count)];
+                Publisher randomPublisher = _publishers[random.Next(_publishers.Count)];
+
+                Book book = new Book
+                {
+                    Id = x,
+                    Title = $"{_firstword[random.Next(_firstword.Count)]} {_secondword[random.Next(_secondword.Count)]} {_thirdword[random.Next(_thirdword.Count)]}",
+                    AuthorId = randomAuthor.Id,
+                    PublisherId = randomPublisher.Id
+                };
+
                 _books.Add(book);
             }
 
-
         }
-        public List<Author> Authors { get { return _authors; } }
-        public List<Book> Books { get { return _books; } }
+        public List<Author> Authors => _authors;
+        public List<Book> Books => _books;
+        public List<Publisher> Publishers => _publishers;
     }
+    
 }
diff --git a/exercise.webapi/Endpoints/AuthorApi.cs b/exercise.webapi/Endpoints/AuthorApi.cs
new file mode 100644
index 0000000..9e33060
--- /dev/null
+++ b/exercise.webapi/Endpoints/AuthorApi.cs
@@ -0,0 +1,68 @@
+using exercise.webapi.DTO;
+using exercise.webapi.Repository;
+using Microsoft.AspNetCore.Mvc;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class AuthorApi
+    {
+        public static void ConfigureAuthorsApi(this WebApplication app)
+        {
+            var authors = app.MapGroup("/authors");
+
+            authors.MapGet("/", GetAuthors);
+            authors.MapGet("/{id}", GetSingleAuthor);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        public static async Task<IResult> GetAuthors(IAuthorRepository authorRepository)
+        {
+            var authors = await authorRepository.GetAllAuthors();
+
+            // Handle null or empty list
+            if (authors == null || !authors.Any())
+            {
+                return Results.Ok(new List<AuthorReponseDTO>());
+            }
+
+            var authorResponses = authors.Select(author => new AuthorReponseDTO
+            {
+                Id = author.Id,
+                FirstName = author.FirstName,
+                LastName = author.LastName,
+                Email = author.Email,
+                Status = "Success",
+                Books = author.Books?.Select(book => new BookResponseDTO
+                {
+                    Title = book.Title
+                }).ToList() ?? new List<BookResponseDTO>()
+            }).ToList();
+
+            return Results.Ok(authorResponses);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> GetSingleAuthor(IAuthorRepository authorRepository, int id)
+        {
+            var author = await authorRepository.GetAuthorById(id);
+            if (author == null)
+            {
+                return Results.NotFound();
+            }
+            var authorResponse = new AuthorReponseDTO
+            {
+                Id = author.Id,
+                FirstName = author.FirstName,
+                LastName = author.LastName,
+                Email = author.Email,
+                Status = "Success",
+                Books = author.Books.Select(book => new BookResponseDTO
+                {
+                    Title = book.Title
+                }).ToList()
+            };
+            return Results.Ok(authorResponse);
+        }
+    }
+}
diff --git a/exercise.webapi/Endpoints/BookApi.cs b/exercise.webapi/Endpoints/BookApi.cs
index 6758215..3c0306a 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
@@ -8,13 +10,128 @@ public static class BookApi
     {
         public static void ConfigureBooksApi(this WebApplication app)
         {
-            app.MapGet("/books", GetBooks);
+            var books = app.MapGroup("/books");
+
+            books.MapGet("/", GetBooks);
+            books.MapGet("/{id}", GetSingleBook);
+            books.MapPost("/", CreateBook);
+            books.MapPut("/{id}", UpdateBook);
+            books.MapDelete("/{id}", DeleteBook);
         }
 
+        [ProducesResponseType(StatusCodes.Status200OK)]
         private static async Task<IResult> GetBooks(IBookRepository bookRepository)
         {
             var books = await bookRepository.GetAllBooks();
             return TypedResults.Ok(books);
         }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> GetSingleBook(IBookRepository bookRepository, int id)
+        {
+            var book = await bookRepository.GetBookById(id);
+            if (book == null)
+            {
+                return TypedResults.NotFound();
+            }
+
+            return TypedResults.Ok(book);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status400BadRequest)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> CreateBook(
+            IBookRepository bookRepository,
+            IAuthorRepository authorRepository,
+            IPublisherRepository publisherRepository,
+            BookPostDTO bookDto)
+        {
+            if (bookDto == null)
+            {
+                return Results.BadRequest("Invalid book object");
+            }
+
+            // Check author
+            var author = await authorRepository.GetAuthorById(bookDto.AuthorId);
+            if (author == null)
+            {
+                return Results.NotFound($"Author with ID {bookDto.AuthorId} not found");
+            }
+
+            // Check publisher
+            var publisher = await publisherRepository.GetPublisherById(bookDto.PublisherId);
+            if (publisher == null)
+            {
+                return Results.NotFound($"Publisher with ID {bookDto.PublisherId} not found");
+            }
+
+            // Create book
+            var newBook = new Book
+            {
+                Title = bookDto.Title,
+                AuthorId = bookDto.AuthorId,
+                PublisherId = bookDto.PublisherId
+
+            };
+
+            var createdBook = await bookRepository.AddBook(newBook);
+            return Results.Created($"/books/{createdBook.Id}", createdBook);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> UpdateBook(
+            IBookRepository bookRepository,
+            IAuthorRepository authorRepository,
+            IPublisherRepository publisherRepository,
+            int id,
+            BookPutDTO bookDto)
+        {
+            // Find existing book
+            var existingBook = await bookRepository.GetBookByIdAsModel(id);
+            if (existingBook == null)
+            {
+                return Results.NotFound($"Book with ID {id} not found");
+            }
+
+            // Retrieve author of book
+            var author = await authorRepository.GetAuthorById(bookDto.AuthorId);
+            if (author == null)
+            {
+                return Results.NotFound($"Author with ID {bookDto.AuthorId} not found");
+            }
+
+            // Retrieve publisher of book
+            var publisher = await publisherRepository.GetPublisherById(bookDto.PublisherId);
+            if (publisher == null)
+            {
+                return Results.NotFound($"Publisher with ID {bookDto.PublisherId} not found");
+            }
+
+            // Update book
+            existingBook.AuthorId = bookDto.AuthorId;
+            existingBook.PublisherId = bookDto.PublisherId;
+
+            var updatedBook = await bookRepository.UpdateBook(id, existingBook);
+
+            return Results.Created($"/books/{id}", updatedBook);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> DeleteBook(IBookRepository bookRepository, int id)
+        {
+            var book = await bookRepository.GetBookById(id);
+            if (book == null)
+            {
+                return TypedResults.NotFound();
+            }
+
+            await bookRepository.DeleteBook(id);
+
+            return TypedResults.Ok(book);
+        }
     }
 }
diff --git a/exercise.webapi/Endpoints/PublisherApi.cs b/exercise.webapi/Endpoints/PublisherApi.cs
new file mode 100644
index 0000000..3742b46
--- /dev/null
+++ b/exercise.webapi/Endpoints/PublisherApi.cs
@@ -0,0 +1,34 @@
+using exercise.webapi.Repository;
+using Microsoft.AspNetCore.Mvc;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class PublisherApi
+    {
+        public static void ConfigurePublishersApi(this WebApplication app)
+        {
+            var publishers = app.MapGroup("/publishers");
+
+            publishers.MapGet("/", GetPublishers);
+            publishers.MapGet("/{id}", GetSinglePublisher);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> GetPublishers(IPublisherRepository publisherRepository)
+        {
+            var publishers = await publisherRepository.GetAllPublishers();
+            return Results.Ok(publishers);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        public static async Task<IResult> GetSinglePublisher(IPublisherRepository publisherRepository, int id)
+        {
+            var publisher = await publisherRepository.GetPublisherById(id);
+            if (publisher == null)
+            {
+                return Results.NotFound();
+            }
+            return Results.Ok(publisher);
+        }
+    }
+}
diff --git a/exercise.webapi/Models/Book.cs b/exercise.webapi/Models/Book.cs
index 9534929..0c73520 100644
--- a/exercise.webapi/Models/Book.cs
+++ b/exercise.webapi/Models/Book.cs
@@ -9,5 +9,8 @@ public class Book
         
         public int AuthorId { get; set; }
         public Author Author { get; set; }
+
+        public int PublisherId { get; set; }
+        public Publisher Publisher { get; set; }
     }
 }
diff --git a/exercise.webapi/Models/Publisher.cs b/exercise.webapi/Models/Publisher.cs
new file mode 100644
index 0000000..52739b8
--- /dev/null
+++ b/exercise.webapi/Models/Publisher.cs
@@ -0,0 +1,12 @@
+using System.Text.Json.Serialization;
+
+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..5896cb4 100644
--- a/exercise.webapi/Program.cs
+++ b/exercise.webapi/Program.cs
@@ -11,6 +11,8 @@
 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>();
 
 var app = builder.Build();
 
@@ -29,4 +31,6 @@
 
 app.UseHttpsRedirection();
 app.ConfigureBooksApi();
+app.ConfigureAuthorsApi();
+app.ConfigurePublishersApi();
 app.Run();
diff --git a/exercise.webapi/Repository/AuthorRepository.cs b/exercise.webapi/Repository/AuthorRepository.cs
new file mode 100644
index 0000000..2a15b02
--- /dev/null
+++ b/exercise.webapi/Repository/AuthorRepository.cs
@@ -0,0 +1,73 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+using exercise.webapi.DTO;
+using Microsoft.EntityFrameworkCore;
+
+namespace exercise.webapi.Repository
+{
+    public class AuthorRepository : IAuthorRepository
+    {
+        private readonly DataContext _db;
+
+        public AuthorRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+        public async Task<IEnumerable<AuthorGetDTO>> GetAllAuthors()
+        {
+            return await _db.Authors
+                .Include(a => a.Books)
+                .ThenInclude(b => b.Publisher)
+                .Select(a => new AuthorGetDTO
+                {
+                    Id = a.Id,
+                    FirstName = a.FirstName,
+                    LastName = a.LastName,
+                    Email = a.Email,
+                    Books = a.Books.Select(b => new BookGetDTO
+                    {
+                        Id = b.Id,
+                        Title = b.Title,
+                        Author = null, // Prevents circular reference
+                        Publisher = new PublisherGetDTO
+                        {
+                            Id = b.Publisher.Id,
+                            Name = b.Publisher.Name
+                        }
+                    }).ToList()
+                })
+                .ToListAsync();
+        }
+
+
+        public async Task<AuthorGetDTO> GetAuthorById(int id)
+        {
+            return await _db.Authors
+                .Include(a => a.Books)
+                .ThenInclude(b => b.Publisher)
+                .Where(a => a.Id == id)
+                .Select(a => new AuthorGetDTO
+                {
+                    Id = a.Id,
+                    FirstName = a.FirstName,
+                    LastName = a.LastName,
+                    Email = a.Email,
+                    Books = a.Books.Select(b => new BookGetDTO
+                    {
+                        Id = b.Id,
+                        Title = b.Title,
+                        Author = null, // ✅ Prevents circular reference
+                        Publisher = b.Publisher != null ? new PublisherGetDTO
+                        {
+                            Id = b.Publisher.Id,
+                            Name = b.Publisher.Name,
+                            Books = null // ✅ Prevents recursion in Publisher's books
+                        } : null
+                    }).ToList()
+                })
+                .FirstOrDefaultAsync();
+        }
+
+    }
+}
\ No newline at end of file
diff --git a/exercise.webapi/Repository/BookRepository.cs b/exercise.webapi/Repository/BookRepository.cs
index 1f5e64a..fd06a6b 100644
--- a/exercise.webapi/Repository/BookRepository.cs
+++ b/exercise.webapi/Repository/BookRepository.cs
@@ -1,4 +1,5 @@
 using exercise.webapi.Data;
+using exercise.webapi.DTO;
 using exercise.webapi.Models;
 using Microsoft.EntityFrameworkCore;
 
@@ -13,10 +14,93 @@ public BookRepository(DataContext db)
             _db = db;
         }
 
-        public async Task<IEnumerable<Book>> GetAllBooks()
+        public async Task<IEnumerable<BookGetDTO>> GetAllBooks()
         {
-            return await _db.Books.Include(b => b.Author).ToListAsync();
+            return await _db.Books
+                .Include(b => b.Author)
+                .Include(b => b.Publisher)
+                .Select(b => new BookGetDTO
+                {
+                    Id = b.Id,
+                    Title = b.Title,
+                    Author = new AuthorGetDTO
+                    {
+                        Id = b.Author.Id,
+                        FirstName = b.Author.FirstName,
+                        LastName = b.Author.LastName,
+                        Email = b.Author.Email
+                    },
+                    Publisher = new PublisherGetDTO
+                    {
+                        Id = b.Publisher.Id,
+                        Name = b.Publisher.Name
+                    }
+                })
+                .ToListAsync();
 
         }
+
+        public async Task<BookGetDTO> GetBookById(int id)
+        {
+            return await _db.Books
+                .Include(b => b.Author)
+                .Include(b => b.Publisher)
+                .Where(b => b.Id == id)
+                .Select(b => new BookGetDTO
+                {
+                    Id = b.Id,
+                    Title = b.Title,
+                    Author = new AuthorGetDTO
+                    {
+                        Id = b.Author.Id,
+                        FirstName = b.Author.FirstName,
+                        LastName = b.Author.LastName,
+                        Email = b.Author.Email
+                    },
+                    Publisher = new PublisherGetDTO
+                    {
+                        Id = b.Publisher.Id,
+                        Name = b.Publisher.Name
+                    }
+                })
+                .FirstOrDefaultAsync();
+        }
+
+        public async Task<Book?> GetBookByIdAsModel(int id)
+        {
+            return await _db.Books
+                .Include(b => b.Author)
+                .Include(b => b.Publisher)
+                .FirstOrDefaultAsync(b => b.Id == id);
+        }
+
+        public async Task<Book> AddBook(Book book)
+        {
+            await _db.Books.AddAsync(book);
+            await _db.SaveChangesAsync();
+            return book;
+        }
+
+        public async Task<Book> UpdateBook(int id, Book book)
+        {
+            var existingBook = await _db.Books.FindAsync(id);
+
+            existingBook.AuthorId = book.AuthorId;
+            existingBook.AuthorId = book.PublisherId;
+
+            await _db.SaveChangesAsync();
+            return existingBook;
+        }
+
+
+        public async Task<bool> DeleteBook(int id)
+        {
+            var book = await _db.Books.FindAsync(id);
+            _db.Books.Remove(book);
+            await _db.SaveChangesAsync();
+            return true;
+        }
+
+
     }
 }
diff --git a/exercise.webapi/Repository/IAuthorRepository.cs b/exercise.webapi/Repository/IAuthorRepository.cs
new file mode 100644
index 0000000..044a08b
--- /dev/null
+++ b/exercise.webapi/Repository/IAuthorRepository.cs
@@ -0,0 +1,11 @@
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface IAuthorRepository
+    {
+        Task<IEnumerable<AuthorGetDTO>> GetAllAuthors();
+        Task<AuthorGetDTO> GetAuthorById(int id);
+    }
+}
diff --git a/exercise.webapi/Repository/IBookRepository.cs b/exercise.webapi/Repository/IBookRepository.cs
index f860016..7f37140 100644
--- a/exercise.webapi/Repository/IBookRepository.cs
+++ b/exercise.webapi/Repository/IBookRepository.cs
@@ -1,9 +1,15 @@
-using exercise.webapi.Models;
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
 
 namespace exercise.webapi.Repository
 {
     public interface IBookRepository
     {
-        public Task<IEnumerable<Book>> GetAllBooks();
+        Task<IEnumerable<BookGetDTO>> GetAllBooks();
+        Task<BookGetDTO> GetBookById(int id);
+        Task<Book?> GetBookByIdAsModel(int id);
+        Task<Book> AddBook(Book book);
+        Task<Book> UpdateBook(int id, Book book);
+        Task<bool> DeleteBook(int id);
     }
 }
diff --git a/exercise.webapi/Repository/IPublisherRepository.cs b/exercise.webapi/Repository/IPublisherRepository.cs
new file mode 100644
index 0000000..d6e1047
--- /dev/null
+++ b/exercise.webapi/Repository/IPublisherRepository.cs
@@ -0,0 +1,11 @@
+using exercise.webapi.DTO;
+
+namespace exercise.webapi.Repository
+{
+    public interface IPublisherRepository
+    {
+        Task<IEnumerable<PublisherGetDTO>> GetAllPublishers();
+        Task<PublisherGetDTO> GetPublisherById(int id);
+    }
+
+}
diff --git a/exercise.webapi/Repository/PublisherRepository.cs b/exercise.webapi/Repository/PublisherRepository.cs
new file mode 100644
index 0000000..0a5c0fc
--- /dev/null
+++ b/exercise.webapi/Repository/PublisherRepository.cs
@@ -0,0 +1,69 @@
+using exercise.webapi.Data;
+using exercise.webapi.DTO;
+using Microsoft.EntityFrameworkCore;
+
+namespace exercise.webapi.Repository
+{
+    public class PublisherRepository : IPublisherRepository
+    {
+        private readonly DataContext _db;
+
+        public PublisherRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+        public async Task<IEnumerable<PublisherGetDTO>> GetAllPublishers()
+        {
+            return await _db.Publishers
+                .Include(p => p.Books)
+                .ThenInclude(b => b.Author)
+                .Select(p => new PublisherGetDTO
+                {
+                    Id = p.Id,
+                    Name = p.Name,
+                    Books = p.Books.Select(b => new BookGetDTO
+                    {
+                        Id = b.Id,
+                        Title = b.Title,
+                        Author = new AuthorGetDTO
+                        {
+                            Id = b.Author.Id,
+                            FirstName = b.Author.FirstName,
+                            LastName = b.Author.LastName,
+                            Email = b.Author.Email
+                        },
+                        Publisher = null
+                    }).ToList()
+                })
+                .ToListAsync();
+        }
+
+        public async Task<PublisherGetDTO> GetPublisherById(int id)
+        {
+            return await _db.Publishers
+                .Include(p => p.Books)
+                .ThenInclude(b => b.Author)
+                .Where(p => p.Id == id)
+                .Select(p => new PublisherGetDTO
+                {
+                    Id = p.Id,
+                    Name = p.Name,
+                    Books = p.Books.Select(b => new BookGetDTO
+                    {
+                        Id = b.Id,
+                        Title = b.Title,
+                        Author = new AuthorGetDTO
+                        {
+                            Id = b.Author.Id,
+                            FirstName = b.Author.FirstName,
+                            LastName = b.Author.LastName,
+                            Email = b.Author.Email
+                        },
+                        Publisher = null // Prevents circular reference
+                    }).ToList()
+                })
+                .FirstOrDefaultAsync();
+        }
+    }
+}
diff --git a/exercise.webapi/exercise.webapi.csproj b/exercise.webapi/exercise.webapi.csproj
index 0ff4269..ad12bcf 100644
--- a/exercise.webapi/exercise.webapi.csproj
+++ b/exercise.webapi/exercise.webapi.csproj
@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Web">
+<Project Sdk="Microsoft.NET.Sdk.Web">
 
   <PropertyGroup>
     <TargetFramework>net9.0</TargetFramework>
@@ -9,9 +9,14 @@
 
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.0" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="8.0.1" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="9.0.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="9.0.1" />
     <PackageReference Include="Scalar.AspNetCore" Version="2.0.4" />
     <PackageReference Include="Swashbuckle.AspNetCore" Version="6.4.0" />
+    <PackageReference Include="Swashbuckle.AspNetCore.Swagger" Version="7.2.0" />
   </ItemGroup>
 
 </Project>