Drucker., P. F. (1999). Management challenges for the 21st century. New York: HarperBusiness.
Chicago Style aipamenaDrucker., Peter F. Management Challenges for the 21st Century. New York: HarperBusiness, 1999.
MLA aipamenaDrucker., Peter F. Management Challenges for the 21st Century. New York: HarperBusiness, 1999.
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