# ISO week date

> leap week calendar system in which weeks start on a Monday and the first week of a year starts from the Monday closest to 1 January; e.g. Thu. 31 Dec. 2009 is 2009–W53–4

**Wikidata**: [Q2110154](https://www.wikidata.org/wiki/Q2110154)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/ISO_week_date)  
**Source**: https://4ort.xyz/entity/iso-week-date


## References

1. Freebase Data Dumps. 2013