Authority is important in judging the credibility of the author's assertions.
In a trial regarding DNA evidence, a jury gives far more authority to what a genetics specialist has to say compared to someone off the street.
What are the author's credentials?
Is the author affiliated with an educational institution or prominent organization?
Can you find information about the author from reference books or the Internet?
Do other books or articles cite the author?
Use a reference source at the library, such as Who's Who, to find reliable biographical information.
Use the library catalog or an article database to see if the author has written any other books or articles on the topic. Or, look in the dust jacket or preface to find biographical data in a book.
Use a search engine to find an online résumé or page about the author's credentials
If you are using a Web source, locate information about the author by looking in the header or footer or any About the author/About us links. Look for a link to the home page of the Web site where the document resides and parts of the URL for clues regarding the author's affiliation.