《新唐书·列传·卷一百四十四》
郁于死，弟吐于即位，与可突于相互猜忌，不能安定其属下，于是带了公主来朝投奔，皇帝改封他为辽阳郡王，留任宿卫。
郁于死，弟吐于嗣，与可突于有隙，不能定其下，携公主来奔，封辽阳郡王，留宿卫。
Yu died, and his younger brother Tu succeeded him. He was suspicious of each other with Ke Tuyu and could not stabilize his subordinates, so he took the princess to the dynasty to surrender. The emperor changed his name to King of Liaoyang County and kept him as the guards.