《礼记·玉藻》
笏的制作，天子是用美玉；诸侯是用象牙；大夫是用竹，但要用有斑纹的鳖鱼皮来纹饰；士也是用竹，但其下端可以用象牙。
笏：天子以球玉；诸侯以象；大夫以鱼须文竹；士竹本，象可也。
As for the笏, the Emperor’s is made of fine jade, while that of a feudal lord is made of ivory. Dafu’s 笏 is made of bamboo, but adorned with the skin of a variegated tortoise. Shi’s 笏 is also made of bamboo, but the lower end can be made of ivory.