《宋史·列传·卷四十三》
河东马军强大，士兵习惯于擅长驰马奔突，与镇、定州相互为表里，然而东下井陉，不到一百里进入镇、定州了。
河东马强，士习善驰突，与镇、定若表里，然东下井陉，不百里入镇、定矣。
The Hebei cavalry is strong, the soldiers are used to galloping and swift attacks, and they correspond with the troops of Zhending Prefecture; however, by going east down Jingxing, they can reach Zhending Prefecture in less than one hundred _li_.