diff --git a/exercise.webapi/DTO/AuthorDTO.cs b/exercise.webapi/DTO/AuthorDTO.cs
new file mode 100644
index 0000000..c25a923
--- /dev/null
+++ b/exercise.webapi/DTO/AuthorDTO.cs
@@ -0,0 +1,5 @@
+namespace exercise.webapi.DTO
+{
+    public record AuthorGet(int Id, string FirstName, string LastName, string Email, IEnumerable<BookInternal> Books);
+    public record AuthorInternal(int id, string FirstName, string LastName, string Email);
+}
diff --git a/exercise.webapi/DTO/BookDTO.cs b/exercise.webapi/DTO/BookDTO.cs
new file mode 100644
index 0000000..e0172ef
--- /dev/null
+++ b/exercise.webapi/DTO/BookDTO.cs
@@ -0,0 +1,7 @@
+namespace exercise.webapi.DTO
+{
+    public record BookGet(int Id, string Title, AuthorInternal author);
+    public record BookPost(string Title, int AuthorId);
+    public record BookPut(int AuthorId);
+    public record BookInternal(int id, string Title);
+}
diff --git a/exercise.webapi/Endpoints/AuthorApi.cs b/exercise.webapi/Endpoints/AuthorApi.cs
new file mode 100644
index 0000000..d7680b2
--- /dev/null
+++ b/exercise.webapi/Endpoints/AuthorApi.cs
@@ -0,0 +1,75 @@
+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}", GetAuthor);
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> GetAuthors(IAuthorRepository authorRepository)
+        {
+            try
+            {
+                var authors = await authorRepository.GetAllAuthors();
+
+                var atrs = authors.Select(author =>
+                {
+                    return new AuthorGet(
+                    author.Id,
+                    author.FirstName,
+                    author.LastName,
+                    author.Email,
+                    author.Books.Select(b => new BookInternal(
+                        b.Id,
+                        b.Title
+                        )
+                    ));
+                });
+
+                return TypedResults.Ok(atrs);
+            }
+            catch(Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> GetAuthor(IAuthorRepository authorRepository, int id)
+        {
+            try
+            {
+                var author = await authorRepository.GetAuthor(id);
+
+                if (author == null)
+                    return TypedResults.Problem(null);
+
+                AuthorGet atr = new AuthorGet(
+                    author.Id,
+                    author.FirstName,
+                    author.LastName,
+                    author.Email,
+                    author.Books.Select(b => new BookInternal(
+                        b.Id,
+                        b.Title
+                    ))
+                );
+
+                return TypedResults.Ok(atr);
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+    }
+}
diff --git a/exercise.webapi/Endpoints/BookApi.cs b/exercise.webapi/Endpoints/BookApi.cs
index 6758215..78cfce9 100644
--- a/exercise.webapi/Endpoints/BookApi.cs
+++ b/exercise.webapi/Endpoints/BookApi.cs
@@ -1,5 +1,11 @@
-using exercise.webapi.Models;
+using System;
+using System.Security.Principal;
+using exercise.webapi.DTO;
+using exercise.webapi.Models;
 using exercise.webapi.Repository;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.Mvc.TagHelpers;
 using static System.Reflection.Metadata.BlobBuilder;
 
 namespace exercise.webapi.Endpoints
@@ -8,13 +14,119 @@ 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.MapPut("/{id}", UpdateBook);
+            books.MapDelete("/{id}", DeleteBook);
+            books.MapPost("/", AddBook);
         }
 
+        [ProducesResponseType(StatusCodes.Status200OK)]
         private static async Task<IResult> GetBooks(IBookRepository bookRepository)
         {
-            var books = await bookRepository.GetAllBooks();
-            return TypedResults.Ok(books);
+            try
+            {
+                var books = await bookRepository.GetAllBooks();
+
+                var bks = books.Select(book =>
+                {
+                    return new BookGet(
+                    book.Id,
+                    book.Title,
+                    new AuthorInternal(
+                        book.Author.Id,
+                        book.Author.FirstName,
+                        book.Author.LastName,
+                        book.Author.Email
+                        )
+                    );
+                });
+
+                return TypedResults.Ok(bks);
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> GetBook(IBookRepository bookRepository, int id)
+        {
+            try
+            {
+                var book = await bookRepository.GetBook(id);
+
+                BookGet bk = new BookGet(
+                    book.Id,
+                    book.Title,
+                    new AuthorInternal(
+                        book.Author.Id,
+                        book.Author.FirstName,
+                        book.Author.LastName,
+                        book.Author.Email
+                        )
+                    );
+
+                return TypedResults.Ok(bk);
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> UpdateBook(IBookRepository bookRepository, int id, int newAuthorId)
+        {
+            try
+            {
+                return TypedResults.Ok(await bookRepository.UpdateBook(id, newAuthorId));
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+
+        [ProducesResponseType(StatusCodes.Status200OK)]
+        private static async Task<IResult> DeleteBook(IBookRepository bookRepository, int id)
+        {
+            try
+            {
+                return TypedResults.Ok(await bookRepository.DeleteBook(id));
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.Problem(ex.Message);
+            }
+        }
+
+        [ProducesResponseType(StatusCodes.Status201Created)]
+        [ProducesResponseType(StatusCodes.Status400BadRequest)]
+        [ProducesResponseType(StatusCodes.Status404NotFound)]
+        private static async Task<IResult> AddBook(IBookRepository bookRepository, IAuthorRepository authorRepository, BookPost book)
+        {
+            try
+            {
+                if (await authorRepository.GetAuthor(book.AuthorId) == null)
+                    return TypedResults.NotFound("Author not found.");
+
+                Book bk = new Book()
+                {
+                    Title = book.Title,
+                    AuthorId = book.AuthorId
+                };
+                await bookRepository.AddBook(bk);
+
+                return TypedResults.Created($"https://localhost:7054/books/{bk.Id}", bk);
+            }
+            catch (Exception ex)
+            {
+                return TypedResults.BadRequest(ex.Message);
+            }
         }
     }
 }
diff --git a/exercise.webapi/Models/Author.cs b/exercise.webapi/Models/Author.cs
index 9f47878..538988a 100644
--- a/exercise.webapi/Models/Author.cs
+++ b/exercise.webapi/Models/Author.cs
@@ -9,7 +9,7 @@ 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>();
     }
 }
diff --git a/exercise.webapi/Program.cs b/exercise.webapi/Program.cs
index 43dec56..c0ed639 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.ConfigureAuthorsApi();
 app.Run();
diff --git a/exercise.webapi/Repository/AuthorRepository.cs b/exercise.webapi/Repository/AuthorRepository.cs
new file mode 100644
index 0000000..67c4845
--- /dev/null
+++ b/exercise.webapi/Repository/AuthorRepository.cs
@@ -0,0 +1,27 @@
+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<IEnumerable<Author>> GetAllAuthors()
+        {
+            return await _db.Authors.Include(a => a.Books).ToListAsync();
+
+        }
+
+        public async Task<Author> GetAuthor(int id)
+        {
+            return await _db.Authors.Include(a => a.Books).FirstOrDefaultAsync(a => a.Id == id);
+        }
+    }
+}
diff --git a/exercise.webapi/Repository/BookRepository.cs b/exercise.webapi/Repository/BookRepository.cs
index 1f5e64a..9b5663a 100644
--- a/exercise.webapi/Repository/BookRepository.cs
+++ b/exercise.webapi/Repository/BookRepository.cs
@@ -18,5 +18,33 @@ 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<Book> UpdateBook(int id, int newAuthorId)
+        {
+            var book = await _db.Books.FirstOrDefaultAsync(b => b.Id == id);
+            book.AuthorId = newAuthorId;
+            await _db.SaveChangesAsync();
+            return book;
+        }
+
+        public async Task<bool> DeleteBook(int id)
+        {
+            var book = await _db.Books.FirstOrDefaultAsync(b => b.Id == id);
+            _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/IAuthorRepository.cs b/exercise.webapi/Repository/IAuthorRepository.cs
new file mode 100644
index 0000000..64fea74
--- /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<IEnumerable<Author>> GetAllAuthors();
+        public Task<Author> GetAuthor(int id);
+    }
+}
diff --git a/exercise.webapi/Repository/IBookRepository.cs b/exercise.webapi/Repository/IBookRepository.cs
index f860016..06deef9 100644
--- a/exercise.webapi/Repository/IBookRepository.cs
+++ b/exercise.webapi/Repository/IBookRepository.cs
@@ -5,5 +5,9 @@ namespace exercise.webapi.Repository
     public interface IBookRepository
     {
         public Task<IEnumerable<Book>> GetAllBooks();
+        public Task<Book> GetBook(int id);
+        public Task<Book> UpdateBook(int id, int newAuthorId);
+        public Task<bool> DeleteBook(int id);
+        public Task<Book> AddBook(Book book);
     }
 }
diff --git a/exercise.webapi/exercise.webapi.csproj b/exercise.webapi/exercise.webapi.csproj
index 0ff4269..dca11e6 100644
--- a/exercise.webapi/exercise.webapi.csproj
+++ b/exercise.webapi/exercise.webapi.csproj
@@ -8,10 +8,20 @@
   </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="Microsoft.EntityFrameworkCore.Tools" Version="9.0.1">
+      <PrivateAssets>all</PrivateAssets>
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+    </PackageReference>
+    <PackageReference Include="Npgsql.EntityFrameworkCore.PostgreSQL" Version="9.0.3" />
     <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>