before the Nazis cancelled his professorship. Bonn mathematicians and several from outside Bonn are planning to edit Hausdorff's collected papers. Brieskorn is writ ing a biography of Hausdorff. Brieskorn and Walter Purkert are the driving force of the Hausdorff edition. Purkert wrote an essay about the correspondence Alexandroff-Hausdorff which I have used here. A translation into Russian of the whole correspondence is in preparation. References [