Não informado. (1940). Main Currents in Modern Thought. Center for Integrated Education.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Main Currents in Modern Thought. New York: Center for Integrated Education, 1940.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Main Currents in Modern Thought. Center for Integrated Education, 1940.
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