Pollard, S. (1971). The idea of progress: History and society. Penguin Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रPollard, Sidney. The Idea of Progress: History and Society. Penguin Books, 1971.
एमएलए (9वां संस्करण) प्रशस्ति पत्रPollard, Sidney. The Idea of Progress: History and Society. Penguin Books, 1971.
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