《水经注·卷三十一》
淯水又往东南流，经过难县的衡山，往东流经百章郭北面，又往东流，鲁阳关水注入。
淯水又东南流历雉县之衡山，东径百章郭北，又东，鲁阳关水注之。
The Yu River flows southeast again, passing through Hengshan Mountain in Nan County, flowing east through the north of Baizhang Guo, and flowing east again, where Chenyangguan Water injects into it.