Investigate the author's background. Find out if he's written more books and if other scholars have cited him. Find out if he's affiliated with a reputable organization. Analyze his credentials. His degree and experience should correlate with his area of research.
Review the date of publication. Determine if the book or article is outdated. Older books are suitable for humanities, while the sciences require updated research. Verify the edition, as each successive edition will contain updated facts and research.
Identify the book's publisher. University presses are often reputable publishers and reinforces an author's credibility. For less known publishers, investigate the type of books published.
Determine the type of journal. Scholarly journals often use: experts, scholars, academics, high diction, abstracts, summaries and footnotes with citations. Other journals may be written by a staff editor, contain illustrations and use fewer sources. Ask the professor about which journal is allowed.
Identify the author's intended audience. Choose a book aimed for experts, if you have prior knowledge. It should be written in a format suitable for you to understand.
Analyze for objective reasoning. The author's claims should be verifiable. Compare information with other works you've read. Scrutinize information that deviates from the standard viewpoint.
Utilize primary and secondary sources. Determine if the materials presented are raw facts or the author's interpretation of primary sources. Expose yourself to more than one viewpoint.
Analyze the writing style. The writing should be logically organized and non-repetitive. The author's argument should be clearly expressed.
Read book reviews. Note any controversies or disagreements. Review any reference that pertains to your field.