Gaya APA

ZEITHAML, V, A. et al (1990). DELIVERING QUALITY SERVICE; Balancing Customer Perceptions and Expectations . New York: THE FREE PRESS.

Gaya MLA

ZEITHAML, Valarie, A.. et al. "DELIVERING QUALITY SERVICE; Balancing Customer Perceptions and Expectations". New York: THE FREE PRESS, 1990. Text.