Correspondence and other materials pertaining to Selig Perlman may be found especially in Archival Volume 8 but also in Volumes 4 and 18B. Perlman was the author of a major history and a psychologically rich interpretation of labor and trade unionism in the United States ( A History of Trade Unionism in the United States , New York: Macmillan, 1922 and Theory of the Labor Movement , New York: Macmillan, 1928). Published below, thanks again to the generous cooperation and permission of his son, Mark Perlman, is further correspondence, principally from Selig Perlman to his former student, Ben Solomon Stephansky.