Columbia subject headings:
Authors, German--20th century--Correspondence--Congresses.
Hesse, Hermann, 1877-1962--Congresses.
Harvard subject headings:
Hesse, Hermann, 1877-1962--Criticism and interpretation--Congresses.
Princeton subject headings:
Authors, German--20th century--Correspondence--Congresses.
Hesse, Hermann, 1877-1962--Congresses.