《周书·本纪·卷五》
三月丙寅日，将八丁兵改为十二丁兵，全都是每年服一月的兵役。
三月丙寅，改八丁兵为十二丁兵，率岁一月役。
On the bingyin day of the third month, the eight-ding soldiers were changed to twelve-ding soldiers, all serving one month of military service per year.