1. General Topology, revised and completed edition (Heldermann Verlag Berlin, 1987).
2. Naive Mengen und abstrakte Zahlen III – Transfinite Methoden (Bibliographisches Institut, 1979).
3. , and , Foundations of Set Theory, second revised edition (North-Holland, 1973).
4. All uncountable cardinals can be singular
5. Sequential topological conditions in ℝ in the absence of the axiom of choice