《资治通鉴·汉纪·汉纪四十三》
左雄上书说： 九卿的地位，仅次于三公，在大臣行列中，行有佩玉的礼节，动有学校的礼仪。
雄上言： 九卿位亚三事，班在大臣，行有佩玉之节，动有庠序之仪。
Zuo Xiong wrote in his memorial: “The position of the Nine Ministers is second only to the Three Dukes. In the ranks of ministers, they have the etiquette of wearing jade and when they move, they have the etiquette of a school.”