diff --git a/exercise.webapi/DTO/AuthorDTO.cs b/exercise.webapi/DTO/AuthorDTO.cs
new file mode 100644
index 0000000..63415da
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorDTO.cs
@@ -0,0 +1,11 @@
+
+namespace exercise.webapi.DTO
+{
+    public class AuthorDTO
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/AuthorListDTO.cs b/exercise.webapi/DTO/AuthorListDTO.cs
new file mode 100644
index 0000000..24afc73
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorListDTO.cs
@@ -0,0 +1,12 @@
+namespace exercise.webapi.DTO
+{
+    public class AuthorListDTO
+    {
+        public int Id { get; set; }
+        public string FirstName { get; set; }
+        public string LastName { get; set; }
+        public string Email { get; set; }
+        public List<BookListDTO> BookList { get; set; } = new List<BookListDTO>();
+
+    }
+}
diff --git a/exercise.webapi/DTO/BookDTO.cs b/exercise.webapi/DTO/BookDTO.cs
new file mode 100644
index 0000000..f91b3cb
--- /dev/null
+++ b/exercise.webapi/DTO/BookDTO.cs
@@ -0,0 +1,13 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.DTO
+{
+    public class BookDTO
+    {
+        public int Id { get; set; }
+        public string Title { get; set; }
+
+        public int AuthorId { get; set; }
+        public AuthorDTO Author { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookListDTO.cs b/exercise.webapi/DTO/BookListDTO.cs
new file mode 100644
index 0000000..507655f
--- /dev/null
+++ b/exercise.webapi/DTO/BookListDTO.cs
@@ -0,0 +1,8 @@
+namespace exercise.webapi.DTO
+{
+    public class BookListDTO
+    {
+        public int Id { get; set; }
+        public string Title { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookPost.cs b/exercise.webapi/DTO/BookPost.cs
new file mode 100644
index 0000000..a93de84
--- /dev/null
+++ b/exercise.webapi/DTO/BookPost.cs
@@ -0,0 +1,8 @@
+namespace exercise.webapi.DTO
+{
+    public class BookPost
+    {
+        public string Title { get; set; }
+        public int AuthorId { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookPut.cs b/exercise.webapi/DTO/BookPut.cs
new file mode 100644
index 0000000..9a6ab0b
--- /dev/null
+++ b/exercise.webapi/DTO/BookPut.cs
@@ -0,0 +1,8 @@
+namespace exercise.webapi.DTO
+{
+    public class BookPut
+    {
+        public string? Title { get; set; }
+        public int? AuthorId { get; set; }
+    }
+}
diff --git a/exercise.webapi/Endpoints/AuthorApi.cs b/exercise.webapi/Endpoints/AuthorApi.cs
new file mode 100644
index 0000000..6751970
--- /dev/null
+++ b/exercise.webapi/Endpoints/AuthorApi.cs
@@ -0,0 +1,66 @@
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
+using exercise.webapi.Repository;
+
+namespace exercise.webapi.Endpoints
+{
+    public static class AuthorApi
+    {
+        public static void ConfigureAuthorApi(this WebApplication app)
+        {
+            var authors = app.MapGroup("authors");
+            authors.MapGet("/", GetAuthors);
+            authors.MapGet("/{id}", GetAuthor);
+        }
+
+
+        #region Get authors
+        private static async Task<IResult> GetAuthors(IAuthorRepository authorRepository)
+        {
+            //Payload<List<Book>> payload = new Payload<List<Book>>();
+
+
+            var results = await authorRepository.GetAllAuthors();
+            var resultsDTO = results.Select(a => new AuthorListDTO
+            {
+                Id = a.Id,
+                FirstName = a.FirstName,
+                LastName = a.LastName,
+                Email = a.Email,
+                BookList = a.Books.Select(b => new BookListDTO
+                {
+                    Id = b.Id,
+                    Title = b.Title,
+                }).ToList()
+            });
+
+            return TypedResults.Ok(resultsDTO);
+        }
+
+        public static async Task<IResult> GetAuthor(IAuthorRepository authorRepository, int id)
+        {
+            var author = await authorRepository.GetAuthor(id);
+            if (author == null)
+            {
+                return Results.NotFound();
+            }
+            var authorDTO = new AuthorListDTO
+            {
+                Id = author.Id,
+                FirstName = author.FirstName,
+                LastName = author.LastName,
+                Email = author.Email,
+                BookList = author.Books.Select(b => new BookListDTO
+                {
+                    Id = b.Id,
+                    Title = b.Title,
+
+                }).ToList()
+            };
+            return Results.Ok(authorDTO);
+
+        }
+        #endregion
+
+    }
+}
diff --git a/exercise.webapi/Endpoints/BookApi.cs b/exercise.webapi/Endpoints/BookApi.cs
index 6758215..ce90ca0 100644
--- a/exercise.webapi/Endpoints/BookApi.cs
+++ b/exercise.webapi/Endpoints/BookApi.cs
@@ -1,4 +1,6 @@
-using exercise.webapi.Models;
+using System;
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
 using exercise.webapi.Repository;
 using static System.Reflection.Metadata.BlobBuilder;
 
@@ -8,13 +10,145 @@ 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}", GetBook);
+            books.MapPost("/", AddBook);
+            books.MapDelete("/{id}", DeleteBook);
+            books.MapPut("/{id}", UpdateBook);
         }
 
+        #region Get books
         private static async Task<IResult> GetBooks(IBookRepository bookRepository)
         {
-            var books = await bookRepository.GetAllBooks();
-            return TypedResults.Ok(books);
+            //Payload<List<Book>> payload = new Payload<List<Book>>();
+
+
+            var results = await bookRepository.GetAllBooks();
+            var resultsDTO = results.Select(b => new BookDTO
+            {
+                Id = b.Id,
+                Title = b.Title,
+                AuthorId = b.AuthorId,
+                Author = new AuthorDTO
+                {
+                    Id = b.Author.Id,
+                    FirstName = b.Author.FirstName,
+                    LastName = b.Author.LastName,
+                    Email = b.Author.Email
+                }
+            });
+
+            return TypedResults.Ok(resultsDTO);
+        }
+
+        public static async Task<IResult> GetBook(IBookRepository bookRepository, int id)
+        {
+            var book = await bookRepository.GetBook(id);
+            if (book == null)
+            {
+                return Results.NotFound();
+            }
+            var bookDTO = new BookDTO
+            {
+                Id = book.Id,
+                Title = book.Title,
+                AuthorId = book.AuthorId,
+                Author = new AuthorDTO
+                {
+                    Id = book.Author.Id,
+                    FirstName = book.Author.FirstName,
+                    LastName = book.Author.LastName,
+                    Email = book.Author.Email
+                }
+            };
+            return Results.Ok(bookDTO);
+           
         }
+        #endregion
+
+        #region Add book
+        public static async Task<IResult> AddBook(IBookRepository bookRepository,IAuthorRepository authorRepository, BookPost model)
+        {
+            try
+            {
+                var author = await authorRepository.GetAuthor(model.AuthorId);
+                Book book = new Book
+                {
+                    Title = model.Title,
+                    AuthorId = model.AuthorId
+                };
+                
+                
+                await bookRepository.AddBook(book);
+
+                BookDTO book2 = new BookDTO
+                {
+                    Id = book.Id,
+                    Title = model.Title,
+                    AuthorId = model.AuthorId,
+                    Author = new AuthorDTO
+                    {
+                        Id = author.Id,
+                        FirstName = author.FirstName,
+                        LastName = author.LastName,
+                        Email = author.Email
+                    }
+                };
+
+                return TypedResults.Ok(book2);
+            }
+
+            catch (Exception e)
+            {
+                return TypedResults.Problem(e.Message);
+            }
+           
+        }
+        #endregion
+
+        #region Delete book
+        public static async Task<IResult> DeleteBook(IBookRepository bookRepository, int id)
+        {
+            try
+            {
+                var book = await bookRepository.GetBook(id);
+                var result = await bookRepository.DeleteBook(id);
+                if (result)
+                {
+                    return Results.Ok(new { When = DateTime.Now, Status = "Deleted", Title = book.Title, AuthorId = book.AuthorId });
+                }
+                return Results.NotFound();
+            }
+            catch (Exception e)
+            {
+                return TypedResults.Problem(e.Message);
+            }
+           
+        }
+        #endregion
+
+        #region Update book
+        public static async Task<IResult> UpdateBook(IBookRepository bookRepository, IAuthorRepository authorRepository, int id, BookPut model)
+        {
+            try
+            {
+                var book = await bookRepository.GetBook(id);
+                if (book == null)
+                {
+                    return Results.NotFound();
+                }
+                if (model.Title != null) book.Title = model.Title;
+                if (model.AuthorId != null) book.AuthorId = model.AuthorId.Value;
+                await bookRepository.UpdateBook(id, book);
+                return Results.Ok(book);
+            }
+            catch (Exception e)
+            {
+                return TypedResults.Problem(e.Message);
+            }
+        }
+        #endregion
+
     }
 }
diff --git a/exercise.webapi/Models/Author.cs b/exercise.webapi/Models/Author.cs
index 9f47878..9073248 100644
--- a/exercise.webapi/Models/Author.cs
+++ b/exercise.webapi/Models/Author.cs
@@ -8,8 +8,6 @@ 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 ICollection<Book> Books { get; set; } = new List<Book>();
+        public List<Book> Books { get; set; } = new List<Book>();
     }
 }
diff --git a/exercise.webapi/Models/Book.cs b/exercise.webapi/Models/Book.cs
index 9534929..ed76045 100644
--- a/exercise.webapi/Models/Book.cs
+++ b/exercise.webapi/Models/Book.cs
@@ -1,4 +1,5 @@
 using System.ComponentModel.DataAnnotations.Schema;
+using exercise.webapi.DTO;
 
 namespace exercise.webapi.Models
 {
diff --git a/exercise.webapi/Program.cs b/exercise.webapi/Program.cs
index 43dec56..ea294b4 100644
--- a/exercise.webapi/Program.cs
+++ b/exercise.webapi/Program.cs
@@ -11,6 +11,7 @@
 builder.Services.AddSwaggerGen();
 builder.Services.AddDbContext<DataContext>(opt => opt.UseInMemoryDatabase("Library"));
 builder.Services.AddScoped<IBookRepository, BookRepository>();
+builder.Services.AddScoped<IAuthorRepository, AuthorRepository>();
 
 var app = builder.Build();
 
@@ -29,4 +30,5 @@
 
 app.UseHttpsRedirection();
 app.ConfigureBooksApi();
+app.ConfigureAuthorApi();
 app.Run();
diff --git a/exercise.webapi/Repository/AuthorRepository.cs b/exercise.webapi/Repository/AuthorRepository.cs
new file mode 100644
index 0000000..26082ed
--- /dev/null
+++ b/exercise.webapi/Repository/AuthorRepository.cs
@@ -0,0 +1,29 @@
+using exercise.webapi.Data;
+using exercise.webapi.Models;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Internal;
+
+namespace exercise.webapi.Repository
+{
+    public class AuthorRepository : IAuthorRepository
+    {
+        DataContext _db;
+
+        public AuthorRepository(DataContext db)
+        {
+            _db = db;
+        }
+
+        
+        public async Task<IEnumerable<Author>> GetAllAuthors()
+        {
+            return await _db.Authors.Include(a => a.Books).ToListAsync();
+
+        }
+
+        public async Task<Author> GetAuthor(int id)
+        {
+            return await _db.Authors.Include(b => b.Books).FirstAsync(b => b.Id == id);
+        }
+    }
+}
diff --git a/exercise.webapi/Repository/BookRepository.cs b/exercise.webapi/Repository/BookRepository.cs
index 1f5e64a..b0d7cf8 100644
--- a/exercise.webapi/Repository/BookRepository.cs
+++ b/exercise.webapi/Repository/BookRepository.cs
@@ -13,10 +13,44 @@ public BookRepository(DataContext db)
             _db = db;
         }
 
+        public async Task<Book> AddBook(Book book)
+        {
+            await _db.Books.AddAsync(book);
+            await _db.SaveChangesAsync();
+            return book;
+        }
+
+        public async Task<bool> DeleteBook(int id)
+        {
+            var target = await _db.Books.FindAsync(id);
+            _db.Books.Remove(target);
+            await _db.SaveChangesAsync();
+            return true;
+        }
+
         public async Task<IEnumerable<Book>> GetAllBooks()
         {
             return await _db.Books.Include(b => b.Author).ToListAsync();
 
         }
+
+        public async Task<Book> GetBook(int id)
+        {
+            return await _db.Books.Include(b => b.Author).FirstAsync(b => b.Id == id);
+        }
+
+        public async Task<Book> UpdateBook(int id, Book book)
+        {
+            var existingBook = _db.Books.Find(id);
+            if (existingBook != null)
+            {
+                existingBook.Title = book.Title;
+                existingBook.AuthorId = book.AuthorId;
+                _db.Books.Update(book);
+                _db.SaveChanges();
+            }
+            return book;
+
+        }
     }
 }
diff --git a/exercise.webapi/Repository/IAuthorRepository.cs b/exercise.webapi/Repository/IAuthorRepository.cs
new file mode 100644
index 0000000..301169f
--- /dev/null
+++ b/exercise.webapi/Repository/IAuthorRepository.cs
@@ -0,0 +1,12 @@
+using exercise.webapi.Models;
+
+namespace exercise.webapi.Repository
+{
+    public interface IAuthorRepository
+    {
+        public Task<IEnumerable<Author>> GetAllAuthors();
+
+        Task<Author> GetAuthor(int id);
+        
+    }
+}
diff --git a/exercise.webapi/Repository/IBookRepository.cs b/exercise.webapi/Repository/IBookRepository.cs
index f860016..d230009 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();
+
+        Task <Book> GetBook(int id);
+        Task <bool> DeleteBook(int id);
+        Task <Book> AddBook(Book book);
+        Task <Book> UpdateBook(int id, Book book);
     }
 }
diff --git a/exercise.webapi/appsettings.json b/exercise.webapi/appsettings.json
index 63d13d3..c9c4c3c 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-cold-waterfall-a9ntum65.gwc.azure.neon.tech;Database=neondb;Username=neondb_owner;Password=npg_AW3mplMX4dvc"
 
-  }
+    }
 } 
\ No newline at end of file
diff --git a/exercise.webapi/exercise.webapi.csproj b/exercise.webapi/exercise.webapi.csproj
index 0ff4269..152fea4 100644
--- a/exercise.webapi/exercise.webapi.csproj
+++ b/exercise.webapi/exercise.webapi.csproj
@@ -8,10 +8,15 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="8.0.0" />
-    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="8.0.1" />
+    <PackageReference Include="Microsoft.AspNetCore.OpenApi" Version="9.0.1" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore" Version="9.0.1" />
+    <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" Version="7.2.0" />
   </ItemGroup>
 
 </Project>