《新唐书·列传·卷一百三十三》
中人曹知悫，是个富家子弟，为人深沉且有勇谋，贼在长安时，曹知悫带清、浊两谷的人倚山屯守，不降贼人。
中人曹知悫者，富家子，颇沈鸷。贼在长安，知悫以清、浊二谷之人倚山为屯，不屈贼。
Cao Zhique, a go-between, was born to a wealthy family, and was a man of depth and cunning. When the rebels were in Chang'an, Cao Zhique led the people of Qinggu and Zhuogu to garrison on the mountain and did not surrender to the rebels.