diff --git a/src/Entity/Book.php b/src/Entity/Book.php
index 6c1fa40..dbd3ed3 100644
--- a/src/Entity/Book.php
+++ b/src/Entity/Book.php
@@ -86,7 +86,13 @@ public static function getEntitiesFromArray(array $array)
     {
         $entities = array();
         foreach ($array as $object) {
-            $entities[] = self::objectTransformer($object);
+            if (in_array(
+                $object['_type'],
+                array(self::TYPE_PDF, self::TYPE_AUDIO, self::TYPE_VIDEO),
+                true)
+            ) {
+                $entities[] = self::objectTransformer($object);
+            }
         }
 
         return $entities;