魏書
In his annotations to Jiang Ji's biography in the "Sanguozhi", Pei Songzhi recorded that Jiang Ji claimed that there was a line on Cao Teng's tombstone which read: "The Cao clan originated from Zhu". Pei Songzhi also noted that the "Book of Wei" (), the official history of the Cao Wei state, confirmed Jiang Ji's claim.