《资治通鉴·唐纪·唐纪三十九》
冬季，十月，仆固怀恩又引回纥、吐蕃军队到州，白孝德、郭闭城坚守。
冬，十月，怀恩引回纥、吐蕃至晞州，白教德、郭晞闭城拒守。
In the winter, tenth month, Puguhuaien again led Huihe and Tubo troops to Zhou, and Bai Xiaode and Guo defended the city with closed gates.