APA (7th ed.) Citation

Drucker, P. F. (1999). Management challenges for the 21st century. HarperCollins.

Chicago Style (17th ed.) Citation

Drucker, Peter Ferdinand. Management Challenges for the 21st Century. New York: HarperCollins, 1999.

MLA (9th ed.) Citation

Drucker, Peter Ferdinand. Management Challenges for the 21st Century. HarperCollins, 1999.

Warning: These citations may not always be 100% accurate.