[1] How to calculate Easter date (2018-05-19 19:37:14 +09:00) https://web.archive.org/web/20010718233816/http://www.asahi-net.or.jp:80/~ez3k-msym/pascha.htm

[2] How to calculate Easter date (2020-10-12T00:06:21.000Z, 2001-07-18T23:38:17.657Z) http://web.archive.org/web/20010718233816/http://www.asahi-net.or.jp/~ez3k-msym/pascha.htm

[3] グレゴリオ暦での復活祭の計算法の特徴: suchowan's blog, 2022-04-19T07:35:32.000Z https://suchowan.at.webry.info/201302/article_18.html