Before reviewing any publication, including books and scholastic articles, evaluate the sources for their credibility. How have they arrived at their results? Are there any conflicting theories or findings? Reading at this critical level will help you decide whether a publication should or should not be included in your literature review.
Take some time to examine how the contributors are affiliated. Are the researchers connected to a university, a research lab or a pharmaceutical company? Are the authors considered leading experts in their field? Are they promoting special interests?
Make sure the publications you include in your literature review are relevant and within the scope of your topic, in terms of theoretical argument, research methodology, timeframe and currency.
How well is the study designed? Do you see any room for improvement? Do similar studies come to the same conclusion? Have the authors explored the topic from different points of view, or do they rely on a more one-sided argument?