5Frederick F. Reichheld. Lead for Loyalty, Harvard Business Review, July-August 2001.
6Gremler, D. D. and Brown, S. W. Service loyalty: its nature, importance, and implications, in Edvardsson, B. et al.(Eds) , Advancing Service Quality: A Global Perspective,International Service Quality Association, 1996, pp. 171-180.
7Griffin, J., Customer loyalty. How to Earn it and How to Keep it, Lexington Books, New York, 1995.
8Vikas Mittal & Jerome M. Katrichis. Distinctions Between New and Loyalty Customer, Marketing Research, Spring 2000 p26-32.