1. Bruce Joyce and Marsha Weil, Models of Teaching ( Englewood Cliffs, N.J.: Prentice-Hall, Inc., 1972), p. 3.
2. Ronald Lippitt and R.K. White, "An Experimental Study of Leadership and Group Life," in Readings in Social Psychology, ed. T. M. Newcomb and E. E. Hartley (New York : Holt, Rinehart and Winston, 1958 ), pp. 446-511.
3. B.F. Skinner, Beyond Freedom and Dignity (New York: Bantam Books, 1971), pp. 63, 169, 206.