When doing research, you should use a variety of sources such as books, articles from newspapers, magazines, or journals, and websites. 
Evaluating sources is an important skill, much of which is detective work. It is tempting to accept whatever you find first, but learning how to evaluate effectively is a skill you need both for your course papers and for your life. (Adapted from OWL at Purdue's Evaluting Sources)

Tips for Evaluating Sources

Checking for signs of bias

• Does the author or publisher endorse political or religious views that could affect objectivity?
• Is the author or publisher associated with a special-interest group, such as Greenpeace or the National Rifle Association, that might present only one side of an issue?
• Are alternative views presented and addressed? How fairly does the author treat opposing views?
• Does the author’s language show signs of bias?

Assessing an argument

• What is the author’s central claim or thesis?
• How does the author support this claim—with relevant and sufficient evidence or with just a few anecdotes or emotional examples?
• Are statistics consistent with those you encounter in other sources? Have they been used fairly? Does the author explain where the statistics come from? (It is possible to “lie” with statistics by using them selectively or by omitting mathematical details.)
• Are any of the author’s assumptions questionable?
• Does the author consider opposing arguments and refute them persuasively?

Tips for Evaluating resources from: Research & Documentation by Dianne Hacker and Barbara Fister, Gustavus Adolphus College http://bcs.bedfordstmartins.com/resdoc5e/tips-for-evaluating-sources.htm retrieved 8/28/2014