The support for Islamic or Hijri or Hegira calendar in software and standards has improved a lot. The followings provide some references which might be helpful to implement various calendar support, which is crucial if the software or service is to have an international user base.
Unicode Common Locale Data Repository (CLDR) project:
- https://cldr.unicode.org
- https://cldr.unicode.org/development/development-process/design-proposals/islamic-calendar-types
Java Documentation:
- https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/time/chrono/HijrahChronology.html
- https://docs.oracle.com/en/java/javase/19/docs/api/java.base/java/time/chrono/HijrahDate.html
USNO Intro to Calendars:
- https://aa.usno.navy.mil/faq/calendars
- https://aa.usno.navy.mil/faq/islamic
- https://aa.usno.navy.mil/faq/crescent
- Explanatory Supplement to the Astronomical Almanac, 3/e
UK Hydrographic Office:
Wikipedia:
- https://en.wikipedia.org/wiki/Islamic_calendar
- https://en.wikipedia.org/wiki/Tabular_Islamic_calendar
Unicode Locale Data Markup Language (LDML):
