Sentence:  ...No studies have investigated the problem's historic roots. Thus, this paper explores the perspective of “early insiders” through an <WSD>historical</WSD> analysis of autobiographies, biographies, and magazine articles written by and about early US newspaper reporters and editors. 
Meaning of the word marked with <WSD> tags:  Done in the manner of a historian: written as a development over time or in accordance with the historical method.