APA (7th ed.) Zitazioa

Gretz, K. F. (1996). Professional selling: A consultative approach. Irwin.

Chicago Style (17th ed.) Zitazioa

Gretz, Karl F. Professional Selling: A Consultative Approach. Chicago: Irwin, 1996.

MLA (9th ed.) Zitazioa

Gretz, Karl F. Professional Selling: A Consultative Approach. Irwin, 1996.