1. Admissible sets and structures. In: Perspectives in Mathematical Logic, Springer-Verlag, Berlin–Heidelberg–New York 1975.
2. Die hohen Unendlichkeiten und die Axiomatik der Mengenlehre. In: Infinitistic Methods, Proceedings of the Symposium on Foundations of Mathematics, Warsaw 1959, PWN, Warszawa 1961, p. 11–20.
3. On the use of Hilbert's ε-operator. In: Essays on the Foundations of Mathematics, Magnes Press, Jerusalem 1966, p. 156–164.