Drucker, P. F. (1999). Management challenges for the 21st century (First edition.). HarperBusiness.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रDrucker, Peter F. Management Challenges for the 21st Century. First edition. New York: HarperBusiness, 1999.
एमएलए (8वां संस्करण) प्रशस्ति पत्रDrucker, Peter F. Management Challenges for the 21st Century. First edition. HarperBusiness, 1999.
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