/**
  * Returns the book ID by a given ISBN
  */
 function getBookIdByISBN($isbn_search)
 {
     require_once PATH_ACCESS . '/BookManager.php';
     $bookManager = new BookManager();
     try {
         $book_id = $bookManager->getBookIDByISBN($isbn_search);
     } catch (Exception $e) {
         $this->BookInterface->dieError($this->messages['error']['notFound'] . $e->getMessage());
     }
     return $book_id['id'];
 }