Não informado. (1940). Main Currents in Modern Thought. Center for Integrated Education.
Chicago-Zitierstil (17. Ausg.)Não informado. Main Currents in Modern Thought. New York: Center for Integrated Education, 1940.
MLA-Zitierstil (8. Ausg.)Não informado. Main Currents in Modern Thought. Center for Integrated Education, 1940.
Achtung: Diese Zitate sind unter Umständen nicht zu 100% korrekt.