Columbia subject headings:
Authors, German--Correspondence.
Becher, Ulrich, 1910-1990--Correspondence.
Exiles--Correspondence.
Harvard subject headings:
Authors, German--20th century--Correspondence
Becher, Ulrich, 1910-1990--Correspondence.
Exiles--Correspondence.
Princeton subject headings:
Authors, German--Correspondence.
Becher, Ulrich, 1910-1990--Correspondence.
Becher, Ulrich, 1910-1990.
Exiles--Correspondence.