《宋书·志·卷十六》
郑玄说： 椭祭在孟夏之月，夹祭在孟秋之月，现在相承是在十月。
郑玄云： 禘以孟夏，祫以孟秋。 今相承用十月。
Zheng Xuan said: The secondary sacrifice is made in the month of Mengxia, and the intercalary sacrifice is made in the month of Mengqiu. Now it is inherited in October.