Columbia subject headings:
Busoni, Ferruccio, 1866-1924--Correspondence.
Busoni, Gerda, 1862-1956--Correspondence.
Composers--Italy--Correspondence.
Harvard subject headings:
Busoni, Ferruccio, 1866-1924--Correspondence.
Busoni, Gerda, 1862-1956--Correspondence.
Composers--Italy--Correspondence
Princeton subject headings:
Busoni, Ferruccio, 1866-1924--Correspondence.
Busoni, Gerda, 1862-1956--Correspondence.
Composers--Italy--Correspondence.