Columbia subject headings:
Communism--Congresses.
Marx, Karl, 1818-1883--Congresses.
Marx, Karl, 1818-1883--Criticism and interpretation--Congresses.
Marx, Karl, 1818-1883--Influence--Congresses.
Socialism--Congresses.
Harvard subject headings:
Marx, Karl, 1818-1883--Appreciation--Congresses.
Princeton subject headings:
Communism--Congresses.
Marx, Karl, 1818-1883--Congresses.
Marx, Karl, 1818-1883--Criticism and interpretation--Congresses.
Marx, Karl, 1818-1883--Influence--Congresses.
Socialism--Congresses.