Captain R. L. Winton-Wiener, writing care of the U.N. Relief and Rehabilitation Administration, conveyed a message to Alma Mahler on behalf of Franz Theodor Csokor, in a letter dated 1945; the writer Klaus Mann, son of Thomas Mann, apparently conveyed letters between Alma Mahler and Csokor in 1946, while Csokor was living in Rome; Wiedner was a publisher, or on staff at a publishing firm, and was the addressee of 1 letter from Csokor; Gregor Müller was a publisher (Pegasus Verlag) with whom Csokor corresponded, and several of those letters are addressed collectively to Müller's family, or specifically to his children, Klaus and Erika Müller.
From the description of Correspondence with Alma Mahler and Franz Werfel, 1923-1969. (University of Pennsylvania Library). WorldCat record id: 155863112