âMembership Series by Language Federation for the Socialist Party of America: Dues Stamps Sold by Month, January 1917 to 1919.â Document originally produced for the Early American Marxism website (www.marxisthistory.org) detailing federation-by-federation and month-by-month paid memberships of the Socialist Party of America from January 1917 to March 1919. Source of the document are figures in the Socialist Party of America papers at Duke University, which were located by historian Theodore Draper during the process of research for his 1957 book, "The Roots of American Communism." Includes commentary by Tim Davenport. This publication may be freely reproduced for all non-commercial uses, including use in the classroom. Corvallis, OR: 1000 Flowers Publishing, 2007.