1. : Philosophie der Mathematik und Naturwissenschaft. Oldenbourg, München 1966, S. 352.
2. Siehe: : Group Theory and its Application to Physical Problems. Addison-Wesley, Reading, Mass. 1962;
3. : Symmetry. Pergamon, New York 1963;
4. : Set Theory. McGraw-Hill, New York 1964;
5. : General Topology. McGraw-Hill, New York 1965;