Columbia subject headings:
Delbrück, Hans, 1848-1929--Archives--Bibliography.
Delbrück, Hans, 1848-1929--Bibliography--Catalogs.
Deutsche Staatsbibliothek--Catalogs.
Germany--History--Bibliography--Catalogs.
Harvard subject headings:
Delbrück, Hans, 1848-1929--Archives--Bibliography.
Delbrück, Hans, 1848-1929--Bibliography--Catalogs.
Deutsche Staatsbibliothek--Catalogs.
Germany--History--Bibliography--Catalogs.
Princeton subject headings:
Delbrück, Hans, 1848-1929--Correspondence, reminiscences, etc.--Index.