Bishu ershi zhong 祕書二十一種

Bishu ershi zhong 祕書二十一種 (Mishu ershiyi zhong 秘書二十一種, Bishu nianyi zhong 祕書廿一種, Mishu nianyi zhong 秘書廿一種) is a series of collectanea compiled during the mid-Qing period 清 (1644-1911) by Wang Shihan 汪士漢, courtesy name Yinhou 隱侯, from Xin'an 新安.

As the title says, the collection includes 21 "secret" books with a total size of 94 juan. The books date from pre-imperial times down to the Song period 宋 (960-1279), and the texts were carefully collated by Wang. The term "secret" refers to the fact that most of these books were relatively rare at the time and not widely available. The collection was first printed in 1742 according to the series Gujin yishi 古今逸史, and the family Wang republished the book in 1804.