Columbia subject headings:
Civilization--Congresses.
History, Ancient--Congresses.
Social change--History--Congresses.
Harvard subject headings:
Civilization--Congresses
History, Ancient--Congresses
Social change--History--Congresses.
Princeton subject headings:
Africa, North--Civilization--Congresses.
Civilization--Congresses.
Europe--Civilization--Congresses.
History, Ancient--Congresses.
Middle East--Civilization--Congresses.
Social change--History--Congresses.