APA (7th ed.) Citation

ZEITHAML, Berry, & Parasuraman. (1990). Delivering quality service: Balancing customer perceptions and expectations. The Free Press.

Chicago Style (17th ed.) Citation

ZEITHAML, Berry, and Parasuraman. Delivering Quality Service: Balancing Customer Perceptions and Expectations. New York: The Free Press, 1990.

MLA (9th ed.) Citation

ZEITHAML, et al. Delivering Quality Service: Balancing Customer Perceptions and Expectations. The Free Press, 1990.