《资治通鉴·宋纪·宋纪十一》
另外，何承天的历法，是日、月、五星各自都有自己的元。而新的历法则是将日、月、五星的交会以及运行的快慢，全都以上元的岁首作为开始。 
又，承天法，日、月、五星各自有元；今法，交会、迟疾悉以上元岁首为始。 
In addition, He Chengtian's calendar system had its own origin for the sun, moon, and five stars. The new calendar system regarded the intersection of the sun, moon, and five stars and their speed of operation as beginning with the first day of the Shangyuan year.