Columbia subject headings:
Harvard subject headings:
Civilization--History--Congresses.
Imperialism--Congresses
War and civilization--Congresses.
World politics--19th century--Congresses.
World politics--20th century--Congresses
Princeton subject headings:
Civilization--History--Congresses.
Imperialism--Congresses.
War and civilization--Congresses.
World politics--History--19th century.
World politics--History--20th century.