Columbia subject headings:
Harvard subject headings:
Authors, German--20th century--Correspondence
Authors, German--Correspondence
Hacks, Elly, 1896-1972--Correspondence.
Hacks, Peter, 1928-2003--Correspondence.
Hacks, Peter, 1928-2003--Criticism and interpretation.
Hacks, Peter, 1928-2003--Political and social views.
Princeton subject headings:
Hacks, Peter, 1928-2003--Correspondence.