Game Sisi's Library online

How do you cope cute fox Sisi with a backlog of books that she brought only a few hours ago, and tomorrow will bring as much again. She asks you to help her in this case is not easy, in return for which it will permit you to borrow some books for free. She really needs help, and it will be immensely grateful to you for your assistance. Look at all the books and find all duplicate, in pairs opening them.