Columbia subject headings:
Authors, German--20th century--Correspondence.
Hasenclever, Walter, 1890-1940--Correspondence.
Harvard subject headings:
Authors, German--20th century--Correspondence
Hasenclever, Walter, 1890-1940--Correspondence.
Princeton subject headings:
Authors, German--20th century--Correspondence.
Hasenclever, Walter, 1890-1940--Correspondence.