johnston.mark w. (2008). relationship selling. new york: Mcgraw hill.
Chicago Style aipamenajohnston.mark w. Relationship Selling. new york: Mcgraw hill, 2008.
MLA aipamenajohnston.mark w. Relationship Selling. new york: Mcgraw hill, 2008.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.