Some sources state that the number of books Ibn Sina has written is over 240; 153 of these have been discovered. Among his valuable books, the two most well-known books are «al-Shifa», which deals mostly with philosophy, and the five-volume «al-Qānūn Fī al-Tibb», which is a complete medical encyclopedia. The Little Qanun is the model of al-Qānūn.