Books in a library or private collection. The Book of the New Tang Dynasty: "The prosperity of books is more than that of Kaiyuan." Qing Ping can't understand the book "Twenty-four histories, months and days": "There is nothing behind me. The books are in hand and they are all sold. " Mao Dun's Innovation &; lt； Novel Monthly &; gt； Sun is busy every day. He browsed all the books in Jiangnan Library.