5Milgrom, J. and J. Roberts. 1992. Economics, Organization and Management. Englewood Cliffs NJ: Prentice Hall, 191-193
6Jensen, M. C. , and Meckling, W. H.. 1976. Theory of the Firm: Managerial Behavior, Agency Costs and Ownership Structure. Journal of Financial Economics, 3 (4) : 305-360