diff --git a/exercise.webapi/DTO/AuthorDTO.cs b/exercise.webapi/DTO/AuthorDTO.cs
new file mode 100644
index 0000000..fc9adf3
--- /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/AuthorDTONoID.cs b/exercise.webapi/DTO/AuthorDTONoID.cs
new file mode 100644
index 0000000..f95295e
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorDTONoID.cs
@@ -0,0 +1,11 @@
+namespace exercise.webapi.DTO
+{
+    public class AuthorDTONoId
+    {
+        public string FirstName { get; set; }
+
+        public string LastName { get; set; }
+
+        public string Email { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookDTO.cs b/exercise.webapi/DTO/BookDTO.cs
new file mode 100644
index 0000000..e2b7ed3
--- /dev/null
+++ b/exercise.webapi/DTO/BookDTO.cs
@@ -0,0 +1,10 @@
+namespace exercise.webapi.DTO
+{
+    public class BookDTO
+    {
+        public int Id { get; set; }
+        public string Title { get; set; }
+
+        public AuthorDTO author { get; set; }
+    }
+}
diff --git a/exercise.webapi/DTO/BookDTONoAuthorID.cs b/exercise.webapi/DTO/BookDTONoAuthorID.cs
new file mode 100644
index 0000000..25bb918
--- /dev/null
+++ b/exercise.webapi/DTO/BookDTONoAuthorID.cs
@@ -0,0 +1,10 @@
+namespace exercise.webapi.DTO
+{
+    public class BookDTONoAuthorID
+    {
+        public int Id { get; set; }
+        public string Title { get; set; }
+
+        public AuthorDTONoId author { get; set; }
+    }
+}
diff --git a/exercise.webapi/Endpoints/BookApi.cs b/exercise.webapi/Endpoints/BookApi.cs
index 6758215..26e25e9 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 +11,206 @@ public static class BookApi
         public static void ConfigureBooksApi(this WebApplication app)
         {
             app.MapGet("/books", GetBooks);
+            app.MapGet("/books/{id}", GetBook);
+            app.MapPost("/books", AddBook);
+            app.MapPut("/books/{author.id}", UpdateBook);
+            app.MapGet("/authors", GetAuthors);
+            app.MapGet("/authors/{id}", GetAuthorById);
+
         }
 
-        private static async Task<IResult> GetBooks(IBookRepository bookRepository)
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        public static async Task<IResult> GetBooks(IBookRepository bookRepository)
         {
             var books = await bookRepository.GetAllBooks();
-            return TypedResults.Ok(books);
+            List<BookDTO> bookList = new List<BookDTO>();
+
+            foreach (var book in books)
+            {
+                Author auth = await bookRepository.GetAuthor(book.AuthorId);
+
+                BookDTO book1 = new BookDTO
+                {
+                    Id = book.Id,
+                    Title = book.Title,
+                    author = new AuthorDTO
+                    {
+                        Id = auth.Id,
+                        FirstName = auth.FirstName,
+                        LastName = auth.LastName,
+                        Email = auth.Email
+                    }
+                };
+                bookList.Add(book1);
+
+            }
+
+            return TypedResults.Ok(bookList);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        public static async Task<IResult> GetAuthors(IBookRepository bookRepository)
+        {
+            var authors = await bookRepository.GetAllAuthors();
+            List<AuthorDTO> authorList = new List<AuthorDTO>();
+
+            foreach (var author in authors)
+            {
+                IEnumerable<Book> books = await bookRepository.GetBooksByAuthorId(author.Id);
+
+                // Convert book entities to DTOs
+                List<BookDTO> bookDTOs = books.Select(b => new BookDTO
+                {
+                    Id = b.Id,
+                    Title = b.Title
+                }).ToList();
+
+                // Create an AuthorDTO with books
+                AuthorDTO authorDTO = new AuthorDTO
+                {
+                    Id = author.Id,
+                    FirstName = author.FirstName,
+                    LastName = author.LastName,
+                    Email = author.Email,
+                };
+                authorList.Add(authorDTO);
+            }
+
+            return TypedResults.Ok(authorList);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        public static async Task<IResult> GetAuthorById(IBookRepository bookRepository, int authorId)
+        {
+            if (authorId <= 0)
+            {
+                return TypedResults.BadRequest("Invalid author ID.");
+            }
+
+            var author = await bookRepository.GetAuthor(authorId);
+
+            if (author == null)
+            {
+                return TypedResults.NotFound($"Author with ID {authorId} not found.");
+            }
+
+            IEnumerable<Book> books = await bookRepository.GetBooksByAuthorId(author.Id);
+
+
+            List<BookDTO> bookDTOs = books.Select(b => new BookDTO
+            {
+                Id = b.Id,
+                Title = b.Title
+            }).ToList();
+
+            AuthorDTO authorDTO = new AuthorDTO
+            {
+                Id = author.Id,
+                FirstName = author.FirstName,
+                LastName = author.LastName,
+                Email = author.Email,
+            };
+
+            return TypedResults.Ok(authorDTO);
+        }
+
+
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+
+        public static async Task<IResult> GetBook(IBookRepository bookRepository, int id)
+        {
+            var book = await bookRepository.GetBook(id);
+            if (book == null)
+            {
+                return Results.NotFound();
+            }
+
+            Author auth = await bookRepository.GetAuthor(book.AuthorId);
+
+            BookDTO book1 = new BookDTO
+            {
+                Id = book.Id,
+                Title = book.Title,
+                author = new AuthorDTO
+                {
+                    Id = auth.Id,
+                    FirstName = auth.FirstName,
+                    LastName = auth.LastName,
+                    Email = auth.Email
+                }
+            };
+
+            return TypedResults.Ok(book1);
+        }
+
+        [ProducesResponseType(StatusCodes.Status201Created)]
+        public static async Task<IResult> UpdateBook(IBookRepository bookRepository, int id, AuthorDTONoId auth)
+        {
+            var book = await bookRepository.GetBook(id);
+
+            BookDTONoAuthorID book1 = new BookDTONoAuthorID
+            {
+                Id = book.Id,
+                Title = book.Title,
+                author = new AuthorDTONoId
+                {
+                    FirstName = auth.FirstName,
+                    LastName = auth.LastName,
+                    Email = auth.Email
+                }
+            };
+
+            book.Author.FirstName = auth.FirstName;
+            book.Author.LastName = auth.LastName;
+            book.Author.Email = auth.Email;
+
+            await bookRepository.UpdateBook(book);
+
+            return TypedResults.Created($"/books/{book1.Id}", book1);
+        }
+
+        [ProducesResponseType(StatusCodes.Status201Created)]
+        public static async Task<IResult> AddBook(IBookRepository bookRepository, string title, int author_id)
+        {
+            Author auth = await bookRepository.GetAuthor(author_id);
+
+            Book book = new Book
+            {
+                Title = title,
+                Author = auth
+            };
+
+            if (book.Author.Id == 0 || auth == null)
+            {
+                return TypedResults.BadRequest("Author ID is invalid");
+            }
+
+            if (string.IsNullOrWhiteSpace(title))
+            {
+                return TypedResults.BadRequest("Title cannot be empty.");
+            }
+
+
+            await bookRepository.AddBook(book);
+
+            AuthorDTO authDTO = new AuthorDTO {
+                Id = book.AuthorId,
+                FirstName = book.Author.FirstName,
+                LastName = book.Author.LastName,
+                Email = book.Author.Email
+            };
+
+            BookDTO bookDTO = new BookDTO
+            {
+                Id = book.Id,
+                Title = title,
+                author = authDTO
+            };
+
+            return TypedResults.Created($"/books/{book.Id}", bookDTO);
+
         }
     }
 }
diff --git a/exercise.webapi/Models/Author.cs b/exercise.webapi/Models/Author.cs
index 9f47878..ee33def 100644
--- a/exercise.webapi/Models/Author.cs
+++ b/exercise.webapi/Models/Author.cs
@@ -1,4 +1,5 @@
-using System.Text.Json.Serialization;
+using exercise.webapi.DTO;
+using System.Text.Json.Serialization;
 
 namespace exercise.webapi.Models
 {
@@ -9,7 +10,6 @@ public class Author
         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<BookDTO> Books { get; set; } = new List<BookDTO>();
     }
 }
diff --git a/exercise.webapi/Repository/BookRepository.cs b/exercise.webapi/Repository/BookRepository.cs
index 1f5e64a..bf9eafa 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;
 
@@ -18,5 +19,38 @@ 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).FirstOrDefaultAsync(b => b.Id == id);
+        }       
+
+        public async Task<IEnumerable<Author>> GetAllAuthors()
+        {
+            return await _db.Authors.ToListAsync();
+        }
+
+        public async Task<Author> GetAuthor(int id)
+        {
+            return await _db.Authors.FirstOrDefaultAsync(a => a.Id == id);
+        }
+        public async Task<Book> UpdateBook(Book book)
+        {
+            _db.Books.Update(book);
+            await _db.SaveChangesAsync();
+            return book;
+        }
+
+        public async Task<Book> AddBook(Book book)
+        {
+            _db.Books.Add(book);
+            await _db.SaveChangesAsync();
+            return book;
+        }
+
+        public async Task<IEnumerable<Book>> GetBooksByAuthorId(int id)
+        {
+            return await _db.Books.Where(b => b.AuthorId == id).ToListAsync();
+        }
+
     }
 }
diff --git a/exercise.webapi/Repository/IBookRepository.cs b/exercise.webapi/Repository/IBookRepository.cs
index f860016..8b9685e 100644
--- a/exercise.webapi/Repository/IBookRepository.cs
+++ b/exercise.webapi/Repository/IBookRepository.cs
@@ -1,9 +1,21 @@
-using exercise.webapi.Models;
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
 
 namespace exercise.webapi.Repository
 {
     public interface IBookRepository
     {
         public Task<IEnumerable<Book>> GetAllBooks();
+        public Task<Book> GetBook(int id);
+        public Task<IEnumerable<Author>> GetAllAuthors();
+
+
+        public Task<Author> GetAuthor(int id);
+        public Task<Book> AddBook(Book book);
+
+        public Task<Book> UpdateBook(Book book);
+
+        public Task<IEnumerable<Book>> GetBooksByAuthorId(int id);
+
     }
 }
diff --git a/exercise.webapi/exercise.webapi.csproj b/exercise.webapi/exercise.webapi.csproj
index 0ff4269..ec8316d 100644
--- a/exercise.webapi/exercise.webapi.csproj
+++ b/exercise.webapi/exercise.webapi.csproj
@@ -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" 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>