When evaluating any information source, it is important to consider the background of its author.
What are the author's credentials--institutional affiliation (where he or she works), educational background, past writings, or experience?
Is the source written on a topic in the author's area of expertise?
Have you seen the author's name cited in other sources or bibliographies? Respected authors are cited frequently by other scholars. For this reason, always note those names that appear in many different sources.
Is the author associated with a reputable institution or organization?
What are the basic values or goals of the organization or institution?
In addition to the author you need to note the publisher. If the source is published by a university press, it is likely to be scholarly. Although the fact that the publisher is reputable does not necessarily guarantee quality, it does show that the publisher may have high regard for the source being published.