diff --git a/Structural/Adapter/Book.php b/Structural/Adapter/Book.php
index 83079d6..88ce1ad 100644
--- a/Structural/Adapter/Book.php
+++ b/Structural/Adapter/Book.php
@@ -2,25 +2,11 @@
 
 namespace DesignPatterns\Structural\Adapter;
 
-class Book implements BookInterface
+interface Book
 {
-    /**
-     * @var int
-     */
-    private $page;
+    public function turnPage();
 
-    public function open()
-    {
-        $this->page = 1;
-    }
+    public function open();
 
-    public function turnPage()
-    {
-        $this->page++;
-    }
-
-    public function getPage(): int
-    {
-        return $this->page;
-    }
+    public function getPage(): int;
 }
diff --git a/Structural/Adapter/BookInterface.php b/Structural/Adapter/BookInterface.php
deleted file mode 100644
index d79ee1b..0000000
--- a/Structural/Adapter/BookInterface.php
+++ /dev/null
@@ -1,12 +0,0 @@
-<?php declare(strict_types=1);
-
-namespace DesignPatterns\Structural\Adapter;
-
-interface BookInterface
-{
-    public function turnPage();
-
-    public function open();
-
-    public function getPage(): int;
-}
diff --git a/Structural/Adapter/EBookInterface.php b/Structural/Adapter/EBook.php
similarity index 92%
rename from Structural/Adapter/EBookInterface.php
rename to Structural/Adapter/EBook.php
index 1249842..a858cf8 100644
--- a/Structural/Adapter/EBookInterface.php
+++ b/Structural/Adapter/EBook.php
@@ -2,7 +2,7 @@
 
 namespace DesignPatterns\Structural\Adapter;
 
-interface EBookInterface
+interface EBook
 {
     public function unlock();
 
diff --git a/Structural/Adapter/EBookAdapter.php b/Structural/Adapter/EBookAdapter.php
index 08d065a..d71a478 100644
--- a/Structural/Adapter/EBookAdapter.php
+++ b/Structural/Adapter/EBookAdapter.php
@@ -3,20 +3,20 @@
 namespace DesignPatterns\Structural\Adapter;
 
 /**
- * This is the adapter here. Notice it implements BookInterface,
+ * This is the adapter here. Notice it implements Book,
  * therefore you don't have to change the code of the client which is using a Book
  */
-class EBookAdapter implements BookInterface
+class EBookAdapter implements Book
 {
     /**
-     * @var EBookInterface
+     * @var EBook
      */
     protected $eBook;
 
     /**
-     * @param EBookInterface $eBook
+     * @param EBook $eBook
      */
-    public function __construct(EBookInterface $eBook)
+    public function __construct(EBook $eBook)
     {
         $this->eBook = $eBook;
     }
@@ -35,7 +35,7 @@ class EBookAdapter implements BookInterface
     }
 
     /**
-     * notice the adapted behavior here: EBookInterface::getPage() will return two integers, but BookInterface
+     * notice the adapted behavior here: EBook::getPage() will return two integers, but Book
      * supports only a current page getter, so we adapt the behavior here
      *
      * @return int
diff --git a/Structural/Adapter/Kindle.php b/Structural/Adapter/Kindle.php
index 03354a6..e261906 100644
--- a/Structural/Adapter/Kindle.php
+++ b/Structural/Adapter/Kindle.php
@@ -6,7 +6,7 @@ namespace DesignPatterns\Structural\Adapter;
  * this is the adapted class. In production code, this could be a class from another package, some vendor code.
  * Notice that it uses another naming scheme and the implementation does something similar but in another way
  */
-class Kindle implements EBookInterface
+class Kindle implements EBook
 {
     /**
      * @var int
diff --git a/Structural/Adapter/PaperBook.php b/Structural/Adapter/PaperBook.php
new file mode 100644
index 0000000..c988f39
--- /dev/null
+++ b/Structural/Adapter/PaperBook.php
@@ -0,0 +1,26 @@
+<?php declare(strict_types=1);
+
+namespace DesignPatterns\Structural\Adapter;
+
+class PaperBook implements Book
+{
+    /**
+     * @var int
+     */
+    private $page;
+
+    public function open()
+    {
+        $this->page = 1;
+    }
+
+    public function turnPage()
+    {
+        $this->page++;
+    }
+
+    public function getPage(): int
+    {
+        return $this->page;
+    }
+}
diff --git a/Structural/Adapter/README.rst b/Structural/Adapter/README.rst
index 6d1c7e0..5b061e4 100644
--- a/Structural/Adapter/README.rst
+++ b/Structural/Adapter/README.rst
@@ -28,27 +28,27 @@ Code
 
 You can also find this code on `GitHub`_
 
-BookInterface.php
-
-.. literalinclude:: BookInterface.php
-   :language: php
-   :linenos:
-
 Book.php
 
 .. literalinclude:: Book.php
    :language: php
    :linenos:
 
-EBookAdapter.php
+PaperBook.php
 
-.. literalinclude:: EBookAdapter.php
+.. literalinclude:: PaperBook.php
    :language: php
    :linenos:
 
-EBookInterface.php
+EBook.php
 
-.. literalinclude:: EBookInterface.php
+.. literalinclude:: EBook.php
+   :language: php
+   :linenos:
+
+EBookAdapter.php
+
+.. literalinclude:: EBookAdapter.php
    :language: php
    :linenos:
 
diff --git a/Structural/Adapter/Tests/AdapterTest.php b/Structural/Adapter/Tests/AdapterTest.php
index 3b8c076..6e5de56 100644
--- a/Structural/Adapter/Tests/AdapterTest.php
+++ b/Structural/Adapter/Tests/AdapterTest.php
@@ -2,7 +2,7 @@
 
 namespace DesignPatterns\Structural\Adapter\Tests;
 
-use DesignPatterns\Structural\Adapter\Book;
+use DesignPatterns\Structural\Adapter\PaperBook;
 use DesignPatterns\Structural\Adapter\EBookAdapter;
 use DesignPatterns\Structural\Adapter\Kindle;
 use PHPUnit\Framework\TestCase;
@@ -11,7 +11,7 @@ class AdapterTest extends TestCase
 {
     public function testCanTurnPageOnBook()
     {
-        $book = new Book();
+        $book = new PaperBook();
         $book->open();
         $book->turnPage();
 
diff --git a/Structural/Adapter/uml/uml.png b/Structural/Adapter/uml/uml.png
index 2d7db9f..792ac0d 100644
Binary files a/Structural/Adapter/uml/uml.png and b/Structural/Adapter/uml/uml.png differ