Columbia subject headings:
Letter writing, German--History.
Harvard subject headings:
Authors, German--19th century--Correspondence
Authors, German--20th century--Correspondence
German letters--19th century--History and criticism.
German letters--20th century--History and criticism.
German prose literature--19th century--History and criticism.
German prose literature--20th century--History and criticism.
Letters in literature.
Princeton subject headings:
Letter writing, German--History.