APA (7th ed.) Citation

Drucker, P. F. (1985). The effective. Haper Business Essentials.

Chicago Style (17th ed.) Citation

Drucker, Peter F. The Effective. New York: Haper Business Essentials, 1985.

MLA (9th ed.) Citation

Drucker, Peter F. The Effective. Haper Business Essentials, 1985.