1. See for example Karl Popper,The Logic of Scientific Discovery, New York: Basic Books, 1959, pp. 32–33.
2. Carl G. Hempel,Philosophy of Natural Science, Englewood Cliffs, N. J.: Prentice-Hall, 1966, chap. 2.
3. Arthur Pap,An Introduction to the Philosophy of Science, New York: The Free Press, 1962, pp. 142–143.
4. Edward H. Madden.The Structure of Scientific Thought, Boston: Houghton Mifflin, 1960, pp. 3–13.
5. John Patrick Day,Inductive Probability, New York: Humanities Press, 1961, pp. 52–79.