Supernatural Television series?

I have lately been getting into "Supernatural", the television series that comes on the CW. I have noticed that every story is based off of some actual myth or folklore tale, some of them even real events that may or may not have been exaggerated a bit. My question is: Does anyone know the source that they get these tales from (ie: website, book)? Or maybe it is just several sources blended together? I would just like to read the actual articles or excerpts they get these stories from. I know I can google the stories (which I have done), but just wondering if anyone knows the source they use.