Columbia subject headings:
Diplomacy.
International relations.
World politics--19th century.
World politics--20th century.
World politics--To 1900.
Harvard subject headings:
Diplomacy.
International relations
World politics--19th century
World politics--20th century
World politics--To 1900
Princeton subject headings:
Diplomacy.
International relations.
World politics--19th century.
World politics--20th century.
World politics--To 1900.