They are usually bought at the flea market. At that time, when seniors left school, all kinds of books were treated at ultra-low prices. Now I don't think I can do it. Usually seniors leave, but you can go to Xiaoxiao's second-hand bookstore, which is full of used books and the price is good. There are basically books in all majors. Xiaoxiao's second-hand bookstore is opposite the building of Yanda North School 10 (find 65438 70 meters north).