《六韬·豹韬·分险》
大凡险要地带作战的方法是，把武冲战车配置在前，以大盾牌为防护，用材士强弩保障我左右两翼。
 凡险战之法，以武冲为前，大橹为卫；材士强驽，翼吾左右。
The general method of fighting in dangerous areas is to place the Wuchong chariot in front, use a large shield for protection, and use材士强弩to protect our left and right flanks.