《资治通鉴·唐纪·唐纪五十一》
由于方渠、合道、木波都是吐蕃的交通要道，德宗准备在那里筑城，便让人询问宁节度使杨朝晟需要多少兵马，杨朝晟回答说： 宁的兵马足够筑城的了，不必烦劳其他道了。 
上以方渠、合道、木波皆吐蕃要路，欲城之，使问邠宁节度使杨朝晟： 须几何兵？ 对曰： 邠宁兵足以城之，不烦他道。 
Because Fangqu, Hedao and Mupo were all important transportation routes for Tubo, Dezong prepared to build cities there, so he asked Ning's Jiedushi Yang Chaosheng how many soldiers and horses he needed. Yang Chaosheng replied: Ning's soldiers and horses are enough to build the city, no need to bother other roads.