Columbia subject headings:
Composers--Correspondence.
Hindemith, Gertrud, 1900-1967--Correspondence.
Hindemith, Paul, 1895-1963--Correspondence.
Harvard subject headings:
Composers--Correspondence
Hindemith, Gertrud, 1900-1967--Correspondence.
Hindemith, Gertrude, 1900-1967--Correspondence.
Hindemith, Paul, 1895-1963--Correspondence.
Princeton subject headings:
Composers--Correspondence.
Hindemith, Gertrud, 1900-1967--Correspondence.
Hindemith, Paul, 1895-1963. Correspondence.