1. Anderson, A. R. and Belnap, N.Entailment, Princeton University Press, Princeton, 1975.
2. Carnap, R.The Logical Syntax of Language, Kegan Paul, Trench, Trubner & Co., London, 1935.
3. Carnap, R.Logical Foundations of Probability, 2nd edition, The University of Chicago Press, 1962.
4. Gemes, K. ?Horwich and Hempel on Hypothetico-Deductivism?,Philosophy of Science Vol.57, 1990.
5. Gemes, K. ?Hypothetico-Deductivism & The Natural Axiomatization of Theories?,Philosophy of Science, Vol. 60, 1993.