Research Sources

I'm preparing to write a book about thunderstorms, tornadoes and hurricanes. It isn't going to be highly technical, as it's aimed at the younger crowd, junior high to high school age. I want to provide a fun introduction to weather. I'm having a lot of fun writing it so far, but I'm going to need some research sources.

I'll be looking for facts on historical tornadoes, such as the super-outbreak of 1974, survivor accounts and also chaser accounts. I know I'll be able to get a lot of info right here, but I'm also looking for a good source of written materials.

Would a place like Oklahoma University be a good place to start? Any suggestions would be really appreciated. Thanks, in advance!