《汉书·志·沟洫志》
可以考证图书，观察地形，命水工测量高低，在山头上开辟大河，流行于胡人中，向东注入大海。
可案图书，观地形，令水工准高下，开大河上领，出之胡中，东注之海。
Books can be examined to verify this, and investigations made of the terrain. Hydraulic engineers can be called in to survey and make calculations, and a massive canal can be dug through a pass in the mountains. This water will flow among the barbarians and eastward into the sea.