《水经注·卷十七》
羌水往西南流，左有长谷水往西南注入，右有东部水往东南注入。
西南流，左则长谷水西南注之，右则东部水东南入焉。
The Qiang River flows southwest, and on the left, Changgu water flows into the southwest, and on the right, Dongbu water flows into the southeast.