Columbia subject headings:
Historians--Germany--Correspondence.
Kaehler, Siegfried A. (Siegfried August), 1885-1963--Correspondence.
Harvard subject headings:
Historians--Germany--Correspondence
Kaehler, Siegfried A. (Siegfried August), 1885-1963--Correspondence.
Princeton subject headings:
Historians--Germany--Correspondence.
Kaehler, Siegfried A. (Siegfried August), 1885-1963--Correspondence.