APA

Drucker P. F., . (2001). The essential Drucker. New York: HarperBusiness.

Chicago

Drucker Peter Ferdinand, . 2001. The essential Drucker. New York: HarperBusiness.

Harvard

Drucker P. F., . (2001). The essential Drucker. New York: HarperBusiness.

MLA

Drucker Peter Ferdinand, . The essential Drucker. New York: HarperBusiness. 2001.