Check out these tips when deciding to use an online source. Always be skeptical.
Authority: Who is responsible for creating the web page? Is there a publisher or sponsor of the web page? Can you find information about the author and publisher?
Audience: Who is this web site created for? Is the content geared towards an age group or population group?
Accuracy: How does the information compare to other sources?
Content: What is the content of the web site: images, articles, a blog? The type of domain (.edu, .gov, .org) may provide some clues about the information. Can you detect a bias? Are there cited references?
Currency: How recent is the web site? Is there information on when it was last updated?
The American Presidency Project is sponsored by the University of California, Santa Barbara and contains over 100,000 documents related to the study of the Presidency. This includes: full text of the Public Papers of the Presidents, complete inaugural addresses, and state of the union addresses.