《新唐书·列传·卷九十六》
马上挑选沙陀李国昌和契必艹、拓跋等族三千名骑兵，夜晚从马邑出发，早晨登上振武城望敌营，看见十几乘毡车，随从们穿着红绿衣裳，探子说： 这是公主的营帐。 
即选沙陀李国昌及契苾、拓拔杂虏三千骑，夜发马邑，旦登振武城望之，见罽车十余乘，从者硃碧衣，谍者曰： 公主帐也。 
Immediately, three thousand cavalrymen from Shatuo, Li Guochang, Qibei, Tuoba, and other tribes were selected and set off from Mayi at night. In the morning, they ascended Zhenwu City and looked at the enemy camp. They saw more than a dozen felt carts, and their entourage was dressed in red and green clothes. The scout said: "This is the princess's camp."