in its own right. Liu credits the earlier mathematicians Zhang Cang (fl. 165 BCE - d. 142 BCE) and Geng Shouchang (fl. 75 BCE - 49 BCE) (see armillary sphere) with the initial arrangement and commentary on the book, yet Han dynasty records do not indicate the names of any authors of commentary, as they are not mentioned until the 3rd century

The Nine Chapters is an anonymous work, and its