diff --git a/src/AppBundle/Entity/Author.php b/src/AppBundle/Entity/Author.php
new file mode 100644
index 0000000..e603318
--- /dev/null
+++ b/src/AppBundle/Entity/Author.php
@@ -0,0 +1,144 @@
+<?php
+
+namespace AppBundle\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\Common\Collections\ArrayCollection;
+
+/**
+ * Author
+ *
+ * @ORM\Table(name="author")
+ * @ORM\Entity(repositoryClass="AppBundle\Repository\AuthorRepository")
+ */
+class Author
+{
+    /**
+     * @var int
+     *
+     * @ORM\Column(name="id", type="integer")
+     * @ORM\Id
+     * @ORM\GeneratedValue(strategy="AUTO")
+     */
+    private $id;
+
+    /**
+     * @var string
+     *
+     * @ORM\Column(name="firstname", type="string", length=255)
+     */
+    private $firstname;
+
+    /**
+     * @var string
+     *
+     * @ORM\Column(name="lastname", type="string", length=255)
+     */
+    private $lastname;
+
+    /**
+     * @var \Doctrine\Common\Collections\Collection
+     *
+     * @ORM\OneToMany(targetEntity="Book", mappedBy="author", cascade={"persist"})
+     */
+    private $books;
+
+    /**
+     * Get id
+     *
+     * @return int
+     */
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    /**
+     * Set firstname
+     *
+     * @param string $firstname
+     *
+     * @return Author
+     */
+    public function setFirstname($firstname)
+    {
+        $this->firstname = $firstname;
+
+        return $this;
+    }
+
+    /**
+     * Get firstname
+     *
+     * @return string
+     */
+    public function getFirstname()
+    {
+        return $this->firstname;
+    }
+
+    /**
+     * Set lastname
+     *
+     * @param string $lastname
+     *
+     * @return Author
+     */
+    public function setLastname($lastname)
+    {
+        $this->lastname = $lastname;
+
+        return $this;
+    }
+
+    /**
+     * Get lastname
+     *
+     * @return string
+     */
+    public function getLastname()
+    {
+        return $this->lastname;
+    }
+    /**
+     * Constructor
+     */
+    public function __construct()
+    {
+        $this->books = new \Doctrine\Common\Collections\ArrayCollection();
+    }
+
+    /**
+     * Add book
+     *
+     * @param \AppBundle\Entity\Book $book
+     *
+     * @return Author
+     */
+    public function addBook(\AppBundle\Entity\Book $book)
+    {
+        $this->books[] = $book;
+
+        return $this;
+    }
+
+    /**
+     * Remove book
+     *
+     * @param \AppBundle\Entity\Book $book
+     */
+    public function removeBook(\AppBundle\Entity\Book $book)
+    {
+        $this->books->removeElement($book);
+    }
+
+    /**
+     * Get books
+     *
+     * @return \Doctrine\Common\Collections\Collection
+     */
+    public function getBooks()
+    {
+        return $this->books;
+    }
+}
diff --git a/src/AppBundle/Entity/Book.php b/src/AppBundle/Entity/Book.php
new file mode 100644
index 0000000..d9bc13c
--- /dev/null
+++ b/src/AppBundle/Entity/Book.php
@@ -0,0 +1,234 @@
+<?php
+
+namespace AppBundle\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\Common\Collections\ArrayCollection;
+
+/**
+ * Book.
+ *
+ * @ORM\Table(name="book")
+ * @ORM\Entity(repositoryClass="AppBundle\Repository\BookRepository")
+ */
+class Book
+{
+    /**
+     * @var int
+     *
+     * @ORM\Column(name="id", type="integer")
+     * @ORM\Id
+     * @ORM\GeneratedValue(strategy="AUTO")
+     */
+    private $id;
+
+    /**
+     * @var string
+     *
+     * @ORM\Column(name="title", type="string", length=255)
+     */
+    private $title;
+
+    /**
+     * @var int
+     *
+     * @ORM\Column(name="pages", type="integer")
+     */
+    private $pages;
+
+    /**
+     * @var \DateTime
+     *
+     * @ORM\Column(name="publishedAt", type="date")
+     */
+    private $publishedAt;
+
+    /**
+     * @var \Doctrine\Common\Collections\Collection
+     *
+     * @ORM\ManyToMany(
+     *     targetEntity="Category",
+     *     cascade={"persist"}
+     * )
+     * @ORM\JoinTable(
+     *     name="book_has_category",
+     *     joinColumns={
+     *         @ORM\JoinColumn(
+     *             name="book_id",
+     *             referencedColumnName="id"
+     *         )
+     *     },
+     *     inverseJoinColumns={
+     *         @ORM\JoinColumn(
+     *             name="category_id",
+     *             referencedColumnName="id",
+     *             unique=true
+     *         )
+     *     }
+     *  )
+     */
+    private $categories;
+
+    /**
+     * @var Author
+     *
+     * @ORM\ManyToOne(
+     *     targetEntity="Author",
+     *     inversedBy="books",
+     *     cascade={"persist", "remove", "merge"}
+     * )
+     * @ORM\JoinColumn(
+     *     name="author_id",
+     *     referencedColumnName="id"
+     * )
+     */
+    private $author;
+
+    /**
+     * Constructor.
+     */
+    public function __construct()
+    {
+        $this->categories = new \Doctrine\Common\Collections\ArrayCollection();
+    }
+
+    /**
+     * Get id.
+     *
+     * @return int
+     */
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    /**
+     * Set title.
+     *
+     * @param string $title
+     *
+     * @return Book
+     */
+    public function setTitle($title)
+    {
+        $this->title = $title;
+
+        return $this;
+    }
+
+    /**
+     * Get title.
+     *
+     * @return string
+     */
+    public function getTitle()
+    {
+        return $this->title;
+    }
+
+    /**
+     * Set pages.
+     *
+     * @param int $pages
+     *
+     * @return Book
+     */
+    public function setPages($pages)
+    {
+        $this->pages = $pages;
+
+        return $this;
+    }
+
+    /**
+     * Get pages.
+     *
+     * @return int
+     */
+    public function getPages()
+    {
+        return $this->pages;
+    }
+
+    /**
+     * Set publishedAt.
+     *
+     * @param \DateTime $publishedAt
+     *
+     * @return Book
+     */
+    public function setPublishedAt($publishedAt)
+    {
+        $this->publishedAt = $publishedAt;
+
+        return $this;
+    }
+
+    /**
+     * Get publishedAt.
+     *
+     * @return \DateTime
+     */
+    public function getPublishedAt()
+    {
+        return $this->publishedAt;
+    }
+
+    /**
+     * Add category
+     *
+     * @param \AppBundle\Entity\Category $category
+     *
+     * @return Book
+     */
+    public function addCategory(\AppBundle\Entity\Category $category)
+    {
+        $this->categories[] = $category;
+
+        return $this;
+    }
+
+    /**
+     * Remove category
+     *
+     * @param \AppBundle\Entity\Category $category
+     */
+    public function removeCategory(\AppBundle\Entity\Category $category)
+    {
+        $this->categories->removeElement($category);
+    }
+
+    /**
+     * Get categories
+     *
+     * @return \Doctrine\Common\Collections\Collection
+     */
+    public function getCategories()
+    {
+        return $this->categories;
+    }
+
+    /**
+     * Set author
+     *
+     * @param \AppBundle\Entity\Author $author
+     *
+     * @return Book
+     */
+    public function setAuthor(\AppBundle\Entity\Author $author = null)
+    {
+        $this->author = $author;
+
+        return $this;
+    }
+
+    /**
+     * Get author
+     *
+     * @return \AppBundle\Entity\Author
+     */
+    public function getAuthor()
+    {
+        return $this->author;
+    }
+}
diff --git a/src/AppBundle/Entity/Category.php b/src/AppBundle/Entity/Category.php
new file mode 100644
index 0000000..7dc0a22
--- /dev/null
+++ b/src/AppBundle/Entity/Category.php
@@ -0,0 +1,117 @@
+<?php
+
+namespace AppBundle\Entity;
+
+use Doctrine\ORM\Mapping as ORM;
+use Doctrine\Common\Collections\ArrayCollection;
+
+/**
+ * Category
+ *
+ * @ORM\Table(name="category")
+ * @ORM\Entity(repositoryClass="AppBundle\Repository\CategoryRepository")
+ */
+class Category
+{
+    /**
+     * @var int
+     *
+     * @ORM\Column(name="id", type="integer")
+     * @ORM\Id
+     * @ORM\GeneratedValue(strategy="AUTO")
+     */
+    private $id;
+
+    /**
+     * @var string
+     *
+     * @ORM\Column(name="name", type="string", length=255)
+     */
+    private $name;
+
+    /**
+     * @var \Doctrine\Common\Collections\Collection
+     *
+     * @ORM\OneToMany(
+     *     targetEntity="Book",
+     *     mappedBy="categories",
+     *     cascade={"persist"}
+     * )
+     */
+    private $books;
+
+    /**
+     * Get id
+     *
+     * @return int
+     */
+    public function getId()
+    {
+        return $this->id;
+    }
+
+    /**
+     * Set name
+     *
+     * @param string $name
+     *
+     * @return Category
+     */
+    public function setName($name)
+    {
+        $this->name = $name;
+
+        return $this;
+    }
+
+    /**
+     * Get name
+     *
+     * @return string
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+    /**
+     * Constructor
+     */
+    public function __construct()
+    {
+        $this->books = new \Doctrine\Common\Collections\ArrayCollection();
+    }
+
+    /**
+     * Add book
+     *
+     * @param \AppBundle\Entity\Book $book
+     *
+     * @return Category
+     */
+    public function addBook(\AppBundle\Entity\Book $book)
+    {
+        $this->books[] = $book;
+
+        return $this;
+    }
+
+    /**
+     * Remove book
+     *
+     * @param \AppBundle\Entity\Book $book
+     */
+    public function removeBook(\AppBundle\Entity\Book $book)
+    {
+        $this->books->removeElement($book);
+    }
+
+    /**
+     * Get books
+     *
+     * @return \Doctrine\Common\Collections\Collection
+     */
+    public function getBooks()
+    {
+        return $this->books;
+    }
+}
diff --git a/src/AppBundle/Repository/AuthorRepository.php b/src/AppBundle/Repository/AuthorRepository.php
new file mode 100644
index 0000000..fdf7c3d
--- /dev/null
+++ b/src/AppBundle/Repository/AuthorRepository.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace AppBundle\Repository;
+
+/**
+ * AuthorRepository
+ *
+ * This class was generated by the Doctrine ORM. Add your own custom
+ * repository methods below.
+ */
+class AuthorRepository extends \Doctrine\ORM\EntityRepository
+{
+}
diff --git a/src/AppBundle/Repository/BookRepository.php b/src/AppBundle/Repository/BookRepository.php
new file mode 100644
index 0000000..8244470
--- /dev/null
+++ b/src/AppBundle/Repository/BookRepository.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace AppBundle\Repository;
+
+/**
+ * BookRepository
+ *
+ * This class was generated by the Doctrine ORM. Add your own custom
+ * repository methods below.
+ */
+class BookRepository extends \Doctrine\ORM\EntityRepository
+{
+}
diff --git a/src/AppBundle/Repository/CategoryRepository.php b/src/AppBundle/Repository/CategoryRepository.php
new file mode 100644
index 0000000..e6d8327
--- /dev/null
+++ b/src/AppBundle/Repository/CategoryRepository.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace AppBundle\Repository;
+
+/**
+ * CategoryRepository
+ *
+ * This class was generated by the Doctrine ORM. Add your own custom
+ * repository methods below.
+ */
+class CategoryRepository extends \Doctrine\ORM\EntityRepository
+{
+}