Moonwise: New Easter Dates: Website by William Morris listing the
Easter Sunday dates from 1997 to 2105, according to the Orthodox (Julian)
reckoning, the Gregorian reckoning and the Aleppo 1997 Proposal for the
Calculation of Easter.
Les textes constitutifs du calendrier grégorien: Rodolphe Audette’s
website on the history of the Gregorian calendar and Easter reckoning is
currently off-line. This link is a mirror of Rodolphe Audette’s website on
the website of Henk Reints. A Dutch translation can be found
Calendar Conversion Software
Calendar Tools: Online calculator by O. Lieberknecht gives indiction
and year according to various styles.