== Causes of autism == 

 Hi Sara. Thank you for your recent edits to this article. However, for medical articles there are strict guidelines regarding suitable references which can be found at WP:MEDRS. Generally speaking, review articles published in respected medical journals are the preferred source. http://www.ncbi.nlm.nih.gov/pubmed/ might be a good place to start your search. WP:MEDMOS is also a good style guide for medical articles. I hope you continue to contribute.