《隋书·列传·卷四十三》
皇上对此感到很惊奇，令杨素和通术数的人士立议六十一件事，都是用旧历书难以解释的，让刘晖和胄玄等人细加辨析。
令杨素与术数人立议六十一事，皆旧法久难通者，令晖与胄玄等辩析之。
The emperor was very surprised by this. He ordered Yang Su and those who were familiar with the art of counting to propose 61 things, which were all difficult to explain in the old calendar, and asked Liu Hui and Zhouxuan to analyze them carefully.