medline ect...

Alright I need some help, where do you all go for research online. Im going to be helping on a major project where I’m considered the supplement expert. any sites, sources.
Also if anyone knows any teen 12-17 or so female sites that contain info on supplements let me know. This project is focusing on that age groups ability to be affected by media advertising in context of diet and supplement productions. Any suggestions info would be greatly appreciated, thanks Ed