I want to add some parameters to my URLs so that I can identify if a page was opened by a visitor clicking on a homepage link, the top navigation, the bottom navigation, etc. So something like:

* <http://url.com/article/123?ref=topnav>
* <http://url.com/article/123?ref=bottomnav>
* ..://url.com/article/123?ref=homepage

(can't post more than two links here)

However, I want to make sure that the search engine does not thing this is a separate page and that I have a lot of duplicate content on my page. I figured there is some "Industry Standard" way of doing this, to make it clear that my parameters are just internal flags for statistics, and not indicative of different content. But I can't find relevant search results when Googling; not sure how to search for this. 

So my question: is there a way I should name or use URL parameters to ensure search engines are aware of the significance of these links?