Publication Date,

If your source has more than one version or edition and lists multiple publication dates, cite the date for the version that you consulted.

Format the date by day, month, year using the abbreviation for the month (e.g. 12 Dec. 2015). If parts of the date are missing just use what is given to you. If a time is given (you might see this on a web page), add it after the date  (e.g. 22 May 2015, 1:00 p.m.). The publication date is followed by a comma.

If there is no date simply leave it out.