If you come across a website that will not let you access information without a "donation"...RUN AWAY!
Databases...Go here first! Then return AGAIN!
Go to these databases for good background information that will help you choose a topic for investigation then RETURN to find resources for the literature review and deeper understanding of your topic.
A comprehensive selection of the finest science content available. Science in Context features authoritative information for assignments and projects, and provides detailed coverage of popular subjects from obesity to endangered species. Full-text articles from national and global newspapers, magazines and journals and a media-rich selection of videos, audios, podcasts, images and interactives.
Science.gov searches over 60 databases and over 2,200 scientific websites to provide users with access to more than 200 million pages of authoritative federal science information including research and development results.