《新唐书·列传·卷九十一》
杜慆听到危难将到来，加高加固城墙，挖深护城河，察看作战器械，无微不至。
慆之闻难，完濬城隍，阅器械无不具。
When Du Jue heard that the danger was coming, he raised and heightened the city wall, dug deep the moat, and inspected the war weapons, leaving no detail unattended