Gaya APA

Zeithaml, V, A. (1990). Delivering quality service : Balancing customer perceptions and expectations . New york, London: The Free Press, Collier Macmillan Publishers.

Gaya MLA

Zeithaml, Valarie, A.. "Delivering quality service : Balancing customer perceptions and expectations". New york, London: The Free Press, Collier Macmillan Publishers, 1990. Text.