《资治通鉴·唐纪·唐纪五十一》
如今方渠、合道、木波三城离吐蕃的疆境更为迫近，需要的人马自当是加倍的了，事情反而相反，这是为什么呢？ 
今三城尤逼虏境，兵当倍之，事更相反，何也？ 
Now the three cities of Fangqu, Hedao and Mupo are closer to the border of Tubo, and the manpower needed will naturally be doubled. On the contrary, why is it the other way around?