Columbia subject headings:
Communism--United States--History.
Communists--United States--History.
Socialism--United States--History.
Socialists--United States--History.
Harvard subject headings:
Communism--United States--History
Communists--United States--History.
Socialism--United States
Socialism--United States--History
Socialists--United States--History.
Princeton subject headings:
Communism--United States--History.
Communists--United States--History.
Socialism--United States--History.
Socialists--United States--History.