Columbia subject headings:
Harvard subject headings:
China--Civilization--20th century.
Russia (Federation)--Civilization--20th century.
United States--Civilization--20th century.
Princeton subject headings:
China--Civilization--1949-
China--Politics and government--1976-.
Soviet Union--Civilization.
Soviet Union--Politics and government--1945-1991.
United States--Civilization--1970-
United States--Politics and government--20th century.