Columbia subject headings:
Benn, Gottfried, 1886-1956.
Harvard subject headings:
Benn, Gottfried, 1886-1956--Correspondence.
Benn, Gottfried, 1886-1956.
Schwedhelm, Karl, 1915-1988--Correspondence.
Princeton subject headings:
Benn, Gottfried, 1886-1956--Criticism and interpretation.