《新唐书·列传·卷一百四十七》
将军队开到青溪关，秘密带领人马伐木开路。在雪坡上辟路，虽是盛夏，仍有两千士卒冻死。
以军缀青溪关，密引众伐木开道，径雪岥，盛夏，卒冻死者二千人。
The army advanced to Qingxiguan and secretly led men and horses to cut trees and open roads. When clearing the road on the snowy slope, even in the middle of summer, two thousand soldiers froze to death.