《汉书·传·卫青霍去病传》
这年秋天，卫青又率领三万骑兵攻打匈奴，出兵雁门关，李息出兵代郡。
其秋，青复将三万骑出雁门，李息出代郡。
In the autumn of the same year, Wei Qing led 30,000 cavalry to attack the Huns again. He set out from Yanmen Pass, and Li Xi set out from Daijun.