MLA on Evaluating Sources

In the 9th edition of the Modern Language Association (MLA) handbook, these questions are presented to the researcher as a way to evaluate a source:

• Who is the author of the source?
• What is the source?
• How was the source produced?
• Where did you find the source?
• When was the source published?

In particular, the questions "Who is the author?" and "How was the source produced?" work well in evaluating a source.

Ask yourself about the author, "Is the author qualified to address the subject? Does the author draw on appropriate research and make a logical argument? Do you perceive bias or the possibility of it in the author's relation to the subject matter?"

Ask yourself about the source, "How was the source produced? Does it have a recognized publisher or sponsoring organization? Was it subjected to a process of vetting, such as peer review, through which authorities in the field assessed its quality?" 

MLA 9th edition handbook, pages 11-12