[1] 暦Wiki/米国暦 - 国立天文台暦計算室 (2019-06-28 20:49:37 +09:00) https://eco.mtk.nao.ac.jp/koyomi/wiki/CAC6B9F1CEF1.html

[2] History of The Astronomical Almanac (2019-08-10 21:01:24 +09:00) https://aa.usno.navy.mil/publications/docs/asa_history.php