Não informado. (1968). Philosophy and History. Institute for Scientific Co-operation.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Philosophy and History. Tubingen, Alemanha: Institute for Scientific Co-operation, 1968.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Philosophy and History. Institute for Scientific Co-operation, 1968.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.