Columbia subject headings:
Composers--Correspondence.
Gubler, Friedrich T. (Friedrich Traugott), 1900-1965--Correspondence.
Krenek, Ernst, 1900-1991--Correspondence.
Harvard subject headings:
Composers--Correspondence
Gubler, Friedrich T. (Friedrich Traugott), 1900-1965--Correspondence.
Krenek, Ernst, 1900-1991--Correspondence.
Princeton subject headings:
Composers--Austria--Correspondence.
Editors--Germany--Correspondence.
Gubler, Friedrich T. (Friedrich Traugott), 1900-1965--Correspondence.
Krenek, Ernst, 1900---Correspondence.