* Richard Montague, (1961), "Semantic Closure and Non-Finite Axiomatizability I," in "Infinitistic Methods: Proceedings of the Symposium on Foundations of Mathematics", (Warsaw, 2–9 September 1959).
* Richard Montague, 1961, «Semantic Closure and Non-Finite Axiomatizability I,» in "Infinitistic Methods: Proceedings of the Symposium on Foundations of Mathematics", (Warsaw, 2-9 September 1959).