Zeithaml, V. A. (2006). Services marketing ed.4: Integrating customer focus across the firmValarie A. Zeithaml, Mary Jo Bitner. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Zeithaml, Valarie A. Services Marketing Ed.4: Integrating Customer Focus Across the FirmValarie A. Zeithaml, Mary Jo Bitner. McGraw-Hill, 2006.
Lua MLA (8ú heag.)Zeithaml, Valarie A. Services Marketing Ed.4: Integrating Customer Focus Across the FirmValarie A. Zeithaml, Mary Jo Bitner. McGraw-Hill, 2006.
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