《资治通鉴·晋纪·晋纪三十二》
拓跋在白登山打猎，看见一只熊带着几个小熊崽儿，便对冠军将军于栗说： 你以勇猛劲健著名，能捉住它们吗？ 
珪畋于白登山，见熊将数子，谓冠军将军于栗磾曰： 卿名勇健，能搏此乎？ 
Tuoba was hunting on Baideng Mountain and saw a bear carrying several bear cubs, so he said to the champion general Yu Li: You are famous for your bravery and strength, can you catch them?