《汉书·传·魏豹田儋韩王信传》
护军中尉陈平对皇上说： 胡人的兵器是弓矛，请让士兵在每个强弩上加上两个箭头，方向朝外，慢慢地移动，突出包围。 
护军中尉陈平言上曰： 胡者全兵，请令强弩傅两矢外乡，徐行出围。 
The protectorate commander Chen Ping said to the Emperor: "The weapons of the barbarians are bows and spears, please ask the soldiers to fit two arrowheads pointing outwards onto each crossbow, and move out slowly, thereby breaking out of the encirclement."