1. Albrecht K. (1992). The only thing that matters . HarperCollins Publishers Inc. New York N.Y.
2. Albrecht and Zemke. (1985). Service America . Warner Books New York N.Y.
3. Harrington J. (1987). The improvement process . McGraw‐Hill Books Inc. New York N.Y.
4. Juran J. M. (1989). Juran on leadership for quality . The Free Press New York N.Y.
5. The memory jogger . (1988). 2nd Ed. Goal/QPC Methuen Mass.