《论衡·卷二十五·诘术篇》
推算日子的甲乙是用天干地支相配，天干地支又用在时辰上。
甲乙有支干，支干有加时。
The Jia and Yi for calculating days are determined by matching the Heavenly Stems and Earthly Branches, and the Heavenly Stems and Earthly Branches are also used in time calculation.