《资治通鉴·汉纪·汉纪二十五》
我派官员追查，他们都报告说：元延元年，曹宫怀孕，同年十月，在掖庭牛官令舍生下一个孩子。
臣遣吏验问，皆得其状：元延元年，宫有身；其十月，宫乳掖庭牛官令舍。
I assigned officials to investigate this case, and all reports said: Cao Gong was pregnant in the 1st year of Yuanyan. She gave birth to a son at the cowshed of Ye Ting in October of the same year.