[1] New moon - Wikipedia (2020-07-25 22:07:33 +09:00) https://en.wikipedia.org/wiki/New_moon#Lunation_Number
[2] Lunation Number | Project Gutenberg Self-Publishing - eBooks | Read eBooks online, Project Gutenberg, 2020-07-29 15:30:12 +09:00 http://self.gutenberg.org/articles/lunation_number