Hi Calida,

The way you'd reference a particular image from Wikimedia commons is a bit like a Flickr image.

The example we set out for this in our website is seen below

In text

(alexwain 2009)

Reference list

alexwain 2009, Sculpture by the Sea - Elephant, Flickr, viewed 4 November 2010, <http://www.flickr.com/photos/alexwain/4091011517/>.

Format: author year, title, publisher, viewed day month year, <url>.

...So adapting this format we'd get, for Wikimedia commons

author year (sourced from date/time uploaded), title of image, Wikimedia Commons, viewed 19th June 2012, <url>.

Hope this helps, let me know if not

David @ UTS Library

david.litting@uts.edu.au