Xu Shen
Xu Shen had to rely on a large body of sources to collect the thousands of characters and variants that appear in the "Shuowen". Many small script characters were taken from the "Cangjiepian" ( c. 220 BCE); ancient characters were collected from the texts found in Confucius's mansion, and Zhou characters were taken from the "Historian Zhou's Primer" (史籀, dated to c. 578 BCE, the reign of Emperor Xuan).