《新唐书·列传·卷一百四十》
回归时出赤亭，掠凉州，都督杨敬述派属官卢公利，元澄出兵追捕。暾欲谷说： 杨敬述如果守城自固，就与他讲和；如果出兵来追，我们就与之决战，定能有功。 
还出赤亭，掠凉州，都督杨敬述使官属卢公利、元澄等勒兵讨捕，暾欲谷曰： 敬述若城守，当与和。如兵出，吾且决战，必有功。 
On the way back, I left Chitai and looted Liangzhou. The governor Yang Jing and said that he sent his officials Lu Gongli and Yuancheng to pursue and capture them. Tun Yugu said: "If Yang Jing is defending the city independently, make peace with him; if he sends troops to pursue, we will fight him to the death, and we will definitely be successful.