《宋书·列传·卷九十二》
考虑到这县不出银矿，加上俚民都住在洞中，说话像鸟语一般，不熟悉交易的方法，每到买银子的时候，损失又很大。
寻此县自不出银，又俚民皆巢居鸟语，不闲货易之宜，每至买银，为损已甚。
Considering that this county did not produce any silver, and the savage-minority all lived in caves, spoke like birds, and were entirely unfamiliar with trading practices, hence during each silver purchase, they suffered a great loss.