Não informado. (1940). Main Currents in Modern Thought. Center for Integrated Education.
Chicago-referens (17:e uppl.)Não informado. Main Currents in Modern Thought. New York: Center for Integrated Education, 1940.
MLA-referens (8:e uppl.)Não informado. Main Currents in Modern Thought. Center for Integrated Education, 1940.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.