APA (7th ed.) Zitazioa
Ludwig, G. (2004). Power selling: Seven strategies for cracking the sales code. Dearborn Trade Pub..
Chicago Style (17th ed.) Zitazioa
Ludwig, George. Power Selling: Seven Strategies for Cracking the Sales Code. Chicago: Dearborn Trade Pub., 2004.
MLA (9th ed.) Zitazioa
Ludwig, George. Power Selling: Seven Strategies for Cracking the Sales Code. Dearborn Trade Pub., 2004.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.