Columbia subject headings:
Communism--History.
Marx, Karl, 1818-1883.
Proletariat.
Socialism--History.
Harvard subject headings:
Communism--History
Marx, Karl, 1818-1883
Proletariat.
Socialism--History
Princeton subject headings:
Communism--History.
Marx, Karl, 1818-1883.
Proletariat.
Socialism--History.