Columbia subject headings:
Freud, Sigmund, 1856-1939.
Hegel, Georg Wilhelm Friedrich, 1770-1831.
Marx, Karl, 1818-1883.
Harvard subject headings:
Freud, Sigmund, 1856-1939
Hegel, Georg Wilhelm Friedrich, 1770-1831
Marx, Karl, 1818-1883
Princeton subject headings:
Freud, Sigmund, 1856-1939.
Hegel, Georg Wilhelm Friedrich, 1770-1831.
Marx, Karl, 1818-1883.