《水经注·卷二十二》
今天地图上没有城，实际上却还在，西南距许昌旧城约三十五里，民间叫堤。
今图无，而城见存，西南去许昌故城可三十五里。
There is no city on today's map, but in fact it still exists, about thirty-five li southwest of the old city of Xuchang, and is called Di by the local people.