《梦溪笔谈·补笔谈卷二》
宝元元年，西夏大军包围延安七天，延安城几次接近失陷。
宝元元年，党项围延安七日，邻于危者数矣。
In the 1st year of Bao Yuan, the Western Xia army surrounded Yan'an for seven days and Yan'an city became close to being captured several times.