[1] julianday.pdf, 2017-08-11T23:13:49.000Z, 2023-04-21T13:08:51.681Z http://fomalhautpsa.sakura.ne.jp/Science/OgawaKiyohiko/julianday.pdf#page=2

[2] メトン周期 - Wikipedia (2019-03-23 12:42:21 +09:00) https://ja.wikipedia.org/wiki/%E3%83%A1%E3%83%88%E3%83%B3%E5%91%A8%E6%9C%9F#%E5%A4%AA%E9%99%BD%E5%91%A8%E6%9C%9F

[3] orbital period | RADIO音楽生活~♪, 2023-04-21T13:14:31.000Z https://ameblo.jp/radio-duck/entry-10578852178.html