《水经注·卷三十七》
《交州外域记》说：交趾郡边界有扶严究，在郡城以北，渡过一条江，就是这条水了。
《交州外域记》曰：交趾郡界有扶严究，在郡之北，隔渡一江。即是水也。
The "Jiaozhou Waiyu Ji" states that there is Fuyanqiu on the border of Jiaozhi County, north of the city of the county. Cross a river and it is this water.