The fact that it’s in print doesn’t automatically make it a reliable source. When evaluating print sources ask yourself these questions:

Book

• How old is it? Research projects will have different requirements as to how old your sources can be. For example, when dealing with contemporary issues or a current controversy, using outdated sources will likely provide inaccurate information. For example, a book on euthanasia published in 1978 probably isn’t the best choice. While the book may contain useful information for other projects, it does not make sense to use it when there are more current materials available.
• Who is the publisher? Books published by a university press undergo significant editing and review to increase their validity and accuracy. When assessing a book published by a commercial publisher, be aware of vanity presses (companies that authors pay to publish their works, rather than vice versa). Also be cautious about using books labeled as “self-published” or books that are published by specific organizations (such as a corporation or a nonprofit group).
• Is the author objective? Check biographical information included in the book, as well as other sources, to gather information about the author’s background as a way of determining his or her stance on a particular issue. In addition, find out about his or her previous works, past professional experience, affiliations with groups or movements, current employment, and degrees or other credentials.

Periodical

• Is it a scholarly journal or a magazine? Scholarly journals are almost always characterized by no advertisements, longer articles, and the requirement that authors cite the sources they use in writing their articles. Articles submitted to scholarly journals undergo substantial scrutiny by other professionals as a way to increase the clarity and accuracy of the information contained in them. Most scholarly journals are not sold on news-stands, but rather are circulated primarily among the academic community. In contrast, magazines are available for purchase; they tend to contain shorter articles, generally don’t require writers to cite their sources, and contain advertising. Therefore, while magazines may contain relevant information, the content may not always be entirely accurate.
• How old is it? As noted above, dated material can sometimes be inaccurate. Always ask your instructor if you’re uncertain about how old is too old.
• Newspaper article: What do you know about the paper that publishes it? Some newspapers have a discernible political slant, which can often be found by skimming through the headlines or by seeing how others regard the newspaper. For example, The Los Angeles Times is considered a more progressive news source, while its neighbor The Orange County Register is considered to have a libertarian slant.