The book Ganzi 干子 "Master Gan" was a Confucian treatise written during the Jin period 晉 (265-420) by Gan Bao 干寶 (286-336?), who was also the author of the history Jinji 晉紀 (lost), and the story collection Soushenji 搜神記. He also wrote a commentary on the "Book of Changes", the Zhouyi zhu 周易注.
The imperial bibliography Jingjizhi 經籍志 in the official dynastic history Suishu 隋書 lists the book Ganzi with a length of 18 juan that was already lost at that time. The bibliographical chapters in the Jiutangshu 舊唐書 and Xintangshu 新唐書 list the books Zhengwen 正言 and Liyan 立言 that are likewise lost. The preface to the essay Rongzhai xubi 容齋續筆 quotes from Ma Zong's 馬總 (d. 823) book Yilin 意林 that once mentioned the book Ganzi, but the received Yilin does not include such a statement.
The Qing-period 清 (1644-1911) scholar Ma Guohan 馬國翰 (1794-1857) was able to collect some fragments of the book Ganzi from the encyclopaedias Tongdian 通典 and Taiping yulan 太平御覽, as well as the book Jing-Chu suishi ji 荊楚歲時記. The fragment collection is to be found in Ma Guohan's series Yuhan shanfang jiyi shu 玉函山房輯佚書.