Steiner (1892-1966) was an Austrian writer, poet and publisher. Richard von Mises was an Austrian-born mathematician, engineer, and positivist philosopher; he was was Gordon McKay Professor of Aerodynamics and Applied Mathematics at Harvard. His wife Hilda (Geiringer) von Mises was an Austrian mathematics professor. Elisabeth Dorothea (Spiro) Klossowski (known as Baladine Klossowska and by the pseudonym Merline) was the wife of the painter and art historian Erich Klossowski and mother of the painter Balthasar Klossowski (Balthus).
From the guide to the Herbert Steiner correspondence with Richard and Hilda von Mises, 1947-1960., (Houghton Library, Harvard College Library, Harvard University)