《水经注·卷十五》
义熙年间一，刘裕西入长安，率领水军驻扎在洛阳，命令参军戴延之与府舍人虞道元乘船溯流而上，考察洛水的上下流，想查明水军船只能到达的地方。
义熙中，刘公西入长安，舟师所届，次于洛阳，命参军戴延之与府舍人虞道元即舟溯流，穷览洛川，欲知水军可至之处。
In the Yixi year, Liu Yu entered Chang'an from the west and led the navy to station in Luoyang. He ordered the military adviser Dai Yanzhi and the private secretary Yu Daoyuan to take a boat up the river to investigate the upper and lower reaches of the Luo river, with the aim of finding out where the navy's ship could reach.