Okay so an appropriate article would be a reliable one.
- A reliable source will have other websites cited, or it will be a well known place like a scientific magazine, government websites, or Newspaper.
An appropriate article will also have at least 3 points you can use in your writing. Even if they are small things.
Also if the sight is using formal writing, by someone who knows what they are talking about. (again like a scientific magazine written by a biologist) This means websites like "Answers" or "Yahoo answers" are not appropriate or reliable.
Hopefully this helps if you need more help let me know - or if you want me to look at the site I can do that as well if you give me the link.