[1] Milgrom, P.R.; Roberts, J. Economics, organization, and management. Prentice-Hall, 2000, pg. 621
[2]Roberts, J. The modern firm: organizational design for performance and growth. Oxford University Press, 2004, pg. 318
[3]Shim,J.K.; Siegel, J.G. Financial Management. Barron´s´Educational Series, Inc.New York, 2008. pg. 393