《汉书·志·律历志上》
邓平说： 使用阳历，朔日平旦时可见到月亮，是为了方便诸侯王和群臣的朝见。 
平曰： 阳历朔皆先旦月生，以朝诸侯王群臣便。 
Deng Ping said: Using the solar calendar, the moon can be seen at dawn on the first day of the lunar month, in order to facilitate the court visit of the vassal kings and their ministers.