《史记·八书·历书》
夏朝以正月为历正，殷朝以十二月为历正，周朝以十一月为历正。
夏正以正月，殷正以十二月，周正以十一月。
The Xia Dynasty regarded the first month as the start of the calendar, the Yin Dynasty regarded the twelfth month as the start of the calendar, and the Zhou Dynasty regarded the eleventh month as the start of the calendar.