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