Columbia subject headings:
American literature--History and criticism.
United States--Civilization.
United States--Emigration and immigration--History.
United States--Foreign relations--20th century.
Harvard subject headings:
American literature--History and criticism
United States--Civilization.
United States--Emigration and immigration--History.
United States--Foreign relations--20th century.
Princeton subject headings:
United States--Civilization.
United States--History.