A Book by category (traditional Chinese: 類書) is one kind of reference book in ancient China.

• First appeared in Cao Wei for the emperor Cao Pi.
• During Song Dynasty Extensive Records of the Taiping Era and Imperial Readings of the Taiping Era,Prime Tortoise of the Record Bureau.
• During Ming Dynasty, Yongle Encyclopedia,
• Qing Dynasty,Gǔjīn Túshū Jíchéng.