Columbia subject headings:
Harvard subject headings:
Helvétius, 1715-1771.
Holbach, Paul Henri Thiry, baron d', 1723-1789.
Marx, Karl, 1818-1883
Materialism.
Princeton subject headings:
Helvétius, 1715-1771.
Holbach, Paul Henri Thiry, baron d', 1723-1789.
Marx, Karl, 1818-1883.
Materialism.