Biodiesel Systems spam 

You mentioned that the link was only posted once when reverting my edit. If you examine the [user's record|http://en.wikipedia.org/wiki/Special:Contributions/79.78.181.59], the spam I reverted was added to numerous pages related to biodiesel.  The user in question has added numerous refspam links, even after warning and conversation elaborating on why the references were inappropriate.  See WP:REFSPAM.