1. Anderson, A. R. and Belnap, N. D. Jr. Jr., ‘Tautological Entailments’, Philosophical Studies 13 (1962), 9–24: see also Ch. Ill of Anderson and Belnap (1975).
2. Anderson, A. R. and Belnap, N. D. Jr., ‘First Degree Entailments’, Mathematische Annalen 149 (1965), 302–319.
3. Anderson, A. R. and Belnap, N. D. Jr., Entailment: the Logic of Relevance and Necessity, vol. I, Princeton University Press, 1975.
4. Belnap, N. D. Jr., An Analysis of Questions: Preliminary Report, System Development Corporation, Santa Monica, 1963.
5. Belnap, N. D. Jr. Jr., ‘How a Computer Should Think’, Contemporary Aspects of Philosophy, Proceedings of the Oxford International Symposium, 1975. Forthcoming, 1976.