《水经注·卷四十》
郑玄说：鸟鼠之山有鸟，与鼠共同飞行。它们共同居住之处则是同穴之山，这是两座山。
郑玄曰：鸟鼠之山有鸟焉，与鸟飞行而处之。又有止而同穴之山焉，是二山也。
Zheng Xuan said: There are birds on Niaoshu Mountain that fly together with rats. The place where they live together is Tongxue Mountain, which are two mountains.