Johnson, R. H. (1972). The concept of existence in the concluding unscientific postscript. Nijhoff.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रJohnson, Ralph Henry. The Concept of Existence in the Concluding Unscientific Postscript. The Hague: Nijhoff, 1972.
एमएलए (9वां संस्करण) प्रशस्ति पत्रJohnson, Ralph Henry. The Concept of Existence in the Concluding Unscientific Postscript. Nijhoff, 1972.
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