PEPPERS DON. (2005). RETURN ON CUSTOMER. DOUBLEDAY.
Chicago Style aipamenaPEPPERS DON. RETURN ON CUSTOMER. NEW YORK: DOUBLEDAY, 2005.
MLA aipamenaPEPPERS DON. RETURN ON CUSTOMER. DOUBLEDAY, 2005.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.