Beck, Judith. Cognitive Therapy: Basics and Beyond. New York: Guilford Press, 1995.
48
Wittink, Dick, and Guah, M. Marketing research done for Cornerstone Research, Cambridge, MA, 1997.
49
Ilgen, D. R., and Klein, H. J. «Organizational Behavior». In M. R. Rosenzweig and L. W. Porter (Eds), Annual Review of Psychology, vol. 40. Palo Alto, CA: Annual Reviews, 1989.