APA aipamena

Drucker., P. F. (1999). Management challenges for the 21st century. New York: HarperBusiness.

Chicago Style aipamena

Drucker., Peter F. Management Challenges for the 21st Century. New York: HarperBusiness, 1999.

MLA aipamena

Drucker., Peter F. Management Challenges for the 21st Century. New York: HarperBusiness, 1999.