To evaluate sources you need to look at a few different criteria. First, look and see if you can find the author’s name, and credentials. Second, look for the publisher information and what kind of publisher (academic, scholarly or professional organization) they are. Next, think about who the audience is for the source. Is it geared to a specific discipline or a more general public? Then look at the content of the source, does the author use citations? Are their references to other writings? Is there a bibliography? Are conclusions drawn on evidence provided in the source? Finally, make sure you can find the date of publication.

For more information, check the out the UGL guide on evaluating sources.