Evaluating the sources you find is a crucial step in the process of library research. The questions you ask about books, periodical articles, web pages, or multimedia sources are similar whether you're looking at a citation to the item or have the item in hand.
How to Critically Analyze Information Sources
Lists some of the critical questions you should ask when you consider the appropriateness of a particular book, article, media resource, or Web site for your research.
Distinguishing Scholarly from Non-Scholarly Periodicals: A Checklist of Criteria
Shows how to evaluate periodicals by looking at their format, intended audience, and appearance.