《晋书·志·第八章》
后秦姚兴时，孝武太元九年，即甲申年，天水人姜岌造《三纪甲子元历》，大略说： 研治历法的方法，先必须捆究、月的运行，然后才可以上考天时，下察地化。
后秦姚兴时，当孝武太元九年，岁在甲申，天水姜岌造《三纪甲子元历》，其略曰： 治历之道，必审日月之行，然后可以上考天时，下察地化。
During the reign of Yao Xing of the Later Qin, in the ninth year of the Xiaowu Taiyuan period, namely the jiashen year, Jiang Ji from Tianshui County created the "Three Periods Jiazi Yuanli" calendar. The main idea is: The method of studying calendar requires binding together with, and the movement of the moon, then one can observe the time of the heaven and check the change of the earth.