1. Representability in some systems of second order arithmetic;Aczel;Israel J. Math.,1970
2. Some consequences of the axiom of constructibility;Addison;Fund. Math.,1959
3. Non-finite axiomatizability of the second order arithmetic;Apt;Bull. Acad. Polon. Sci.,1972
4. ω-models in analytical hierarchy;Apt;Bull. Acad. Polon. Sci.,1972
5. Infinitistic rules of proof and their semantics;Apt;Bull. Acad. Polon. Sci.,1973