Tschohl, J. (1997). Achieving excellence through customer service. Jaico.
Chicago Style aipamenaTschohl, John. Achieving Excellence Through Customer Service. Bombay: Jaico, 1997.
MLA aipamenaTschohl, John. Achieving Excellence Through Customer Service. Jaico, 1997.
Kontuz: berrikusi erreferentzia hauek erabili aurretik.