When evaluating the quality of an information source, remember to examine:
Purpose / Point of View
Here are some questions to ask yourself for each category:
Currency - How current is the information? Is the age of the publication likely to affect the conclusions drawn by the author?
Reliability - Does this work present you with high quality information? Is your topic treated as the main subject, or is it peripheral? Does the information support or disprove your thesis? Is the resource useful to your research need?
Authority - Who is the author of the work, and what are his/her credentials? Who published the work - a scholarly press, a commercial publisher, or is it self-published? If it is an online resource, can you determine who the author is?
Purpose/Point of View - What is the purpose of the resource? Is it to inform, entertain, etc? Is the purpose clearly outlined in the foreword or introduction? Is the work's audience an expert in the field or a layperson?