1. Ackermann W.: Begründung einer strengen implikation. J. Symb. Log. 21(2), 113–128 (1956)
2. Anderson, A.R., Belnap, N.D. Jr.: Entailment. The logic of relevance and necessity, vol. I. Princeton University Press, Princeton (1975)
3. Batens D., De Clercq K., Kurtonina N.: Embedding and interpolation for some paralogics. The propositional case. Rep. Math. Log. 33, 29–44 (1999)
4. Belnap, N.D.: How a computer should think. In: Ryle, G. (ed.) Contemporary Aspects of Philosophy. Oriel Press Ltd, Stocksfield (1977)
5. Belnap, N.D.: A useful four-valued logic. In: Dunn, J.M., Epstein, G. (eds.) Modern Uses of Multiple-Valued Logic. D. Reidel, Dordrecht (1977)