《资治通鉴·晋纪·晋纪二十七》
慕容楷对慕容绍说： 鲜卑、乌桓以及冀州的民众，本来都是燕国的属臣，如今大业刚刚开始，人心尚未融洽，这就是导致小有不同的原因。
楷谓绍曰： 鲜卑、乌桓及冀州之民，本皆燕臣。今大业始尔，人心未洽，所以小异。
Murong Kai said to Murong Shao: "The Xianbei, Wuhuan and the people of Jizhou were originally the vassals of the Yan Kingdom. Now that the great cause has just begun, the people's hearts have not yet been integrated, which is the reason for the small differences. "