# proleptic Gregorian calendar

> extension of the Gregorian calendar before its introduction

**Wikidata**: [Q1985727](https://www.wikidata.org/wiki/Q1985727)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/Proleptic_Gregorian_calendar)  
**Source**: https://4ort.xyz/entity/proleptic-gregorian-calendar


## References

1. Freebase Data Dumps. 2013