1. Cole Arthur H., Business Enterprise in Its Social Setting, (Cambridge: Harvard University Press, 1951), p. 28.
2. Dewing Arthur Stone, The Financial Policy of Corporations (New York: Ronald Press, 1919), pp. 245–254.
3. Schumpeter Joseph A., The Theory of Economic Development (Cambridge: Harvard University Press, 1934) in Okun E., Studies in Economic Development, pp. 91–94.