• date: Date of referenced source. Can be full date (day, month, and year) or partial date (month and year, season and year, or year). Use same format as other publication dates in the citations.[date 1] Required when year is used to disambiguate {{sfn}} links to multiple-work citations by the same author in the same year.[more] Do not wikilink. Displays after the authors and is enclosed in parentheses. If there is no author, then displays after publisher.. For acceptable date formats, see Help:Citation Style 1 § Dates.
For approximate year, precede with "c. ", like this: |date=c. 1900.

For no date, or "undated", use |date=n.d.
Automatic date formatting: Citation Style 1 and 2 templates, including this template, automatically render dates in all date parameters (such as |date=, |publication-date=, |access-date=, |archive-date=, etc.) except for |orig-date= in the style specified by the article's {{use dmy dates}} or {{use mdy dates}} template. See those templates' documentation for details.
  • year: Year of source being referenced. Use the more flexible |date= parameter instead unless all of the following conditions are met:
    1. The |date= format is YYYY-MM-DD.
    2. The citation requires a CITEREF disambiguator.
  • orig-date: Original publication date or year; displays in square brackets after the date (or year). For clarity, please supply specifics. For example: |orig-date=First published 1859 or |orig-date=Composed 1904. As |orig-date= does not support automatic date formatting, use the same date format as defined by |df= (or, if it exists in the article, by |cs1-dates= of a {{use dmy dates}} or {{use mdy dates}} template), or as used in the |date= parameter. Alias: orig-year, origyear}}
  • df: date format; sets rendered dates to the specified format; does not support date ranges or seasonal dates; overrides the automatic date formatting described above. Accepts one value which may be one of these:
    dmy – set publication dates to day month year format; access- and archive-dates are not modified;
    mdy – as above for month day, year format
    ymd – as above for year initial numeric format YYYY-MM-DD
    dmy-all – set publication, access-, and archive-dates to day month year format;
    mdy-all – as above for month day, year format
    ymd-all – as above for year initial numeric format YYYY-MM-DD
  1. Publication dates in references within an article should all have the same format. This may be a different format from that used for archive and access dates. See MOS:DATEUNIFY.