Many History course assignments require students to consult peer-reviewed/scholarly articles in leading academic History journals. In addition, many will also go beyond that requirement and ask you to only consult peer-reviewed articles authored by a historian. The information below will help you learn more about how to identify peer-reviewed articles and how to best determine if an author holds a PhD in History.
To determine if the author or a book or article is/was a historian you will need to conduct research on the author.
You can begin by doing the following:
1) Go to Google and search the author's first and last name.
2) If the author is still living and working as a historian, she/he will typically have an academic appointment and be listed on a University Department web page which will list their educational credentials and publications.
3) If you cannot find an active faculty listing, you can also consult the following works in the reference area of the Learning Commons which list prominent historians:
The Blackwell Dictionary of Historians by 
Great Historians of the Modern Age by 
The American Historical Association's Guide to Historical Literature by 
A Global Encyclopedia of Historical Writing by 
