1. Czelakowski J.: Matrices, primitive satisfaction and finitely based logics. Studia Logica 42(1), 89–104 (1983)
2. Došen, K., On passing from singular to plural consequences, in E. Orlowska (ed.), Logic at Work: Essays Dedicated to the Memory of Helena Rasiowa, Physica-Verlag, Heidelberg, 1999, pp. 533–547.
3. Gentzen, G., The collected papers of Gerhard Gentzen, in M. E. Szabo (ed.), Volume 55 of Studies in Logic and the Foundations of Mathematics, North-Holland, Amsterdam, 1969.
4. Hacking, I., What is logic?, in D. M. G abbay (ed.), What is a Logical System?, Oxford University Press, Oxford, 1994, pp. 1–33.
5. Payette G., Schotch P.K.: On preserving. Logica Universalis 1(2), 295–310 (2007)