You can edit most of the pages and add yours as an external link, however it's not guaranteed that it won't be removed
wikipedia is like an open source software where the source is open anyone can edite and remove yoru site or it will remain their forever it's just a chance and luck if it would be their forever...
Iv had some luck with getting links from wikipedia. If you can get them to stay there then you can get lots of traffic from it. The key is to add something of value to wikipedia and reference it back to your site....So write something on your site that is unique and informative about the subject then go to wikipedia and add a paragraph related to what you have written on your site, stating some facts and figures and then just add your link as a reference. Iv found that nine times out of ten the links will stay up there if you do this.
I was going to say this exact same thing. If you don't add anything of any value then then your links are likely to be removed. If all we had to do was edit Wikipedia articles and throw our links in there with a guarantee that they'd be there forever, Wikipedia pages would be more links than content.
It is really hard to get backlinks to stick in Wikipedia, you really need to have relevant and unique content that is valuable about the topic being linked from.
Just use facts, if anyone smells a sales pitch your post is deleted and IP blocked! We have several external links to our site from Wikipedia