《史记·八书·平准书》
于是以白鹿皮一尺见方，饰以绣文，制成皮币，直四十万钱，规定王侯宗室来朝觐聘享，玉璧都必须以皮币作衬垫进献，然后礼仪得行。
乃以白鹿皮方尺，缘以藻缋，为皮币，直四十万。王侯宗室朝觐聘享，必以皮币荐璧，然后得行。
Therefore, a piece of white deer skin one foot square was used, decorated with embroidery, and made into a leather coin, which is worth 400,000 coins. It is stipulated that when the princes and clan members come to the court to pay tribute and visit, they must present jade bi with leather coins as a backing, and then the etiquette can be performed.