olemus
aastate nummerduse süsteem Julianuse ja Gregoriuse kalendrites, alguspunktiga AD 1
Wiktionary:
(chronology) the secular equivalent of anno Domini and the Christian Era, the internationally recognized method of numbering years on the Gregorian calendar

ülevaateid
https://en.wikipedia.org/wiki/Common_Era
https://www.druide.com/en/reports/bc-and-ad-bce-and-ce-whats-difference
https://rationalwiki.org/wiki/Common_Era
https://en.wikipedia.org/wiki/Template:Year_in_various_calendars