Answer:
Archival research method
Explanation:
According to my research on different types of research methods , I can say that based on the information provided within the question Dr. McCabe used an Archival research method. This method focuses on searching for and gathering all information from sets of old, non-current, documentation that has been archived by individuals of the past. Which is what Dr. McCabe is doing by gathering information from books published between the 1900's to the 2000's.
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