Columbia subject headings:
Hegel, Georg Wilhelm Friedrich, 1770-1831.
Marx, Karl, 1818-1883.
Unamuno, Miguel de, 1864-1936.
Harvard subject headings:
Hegel, Georg Wilhelm Friedrich, 1770-1831
Marx, Karl, 1818-1883
Unamuno, Miguel de, 1864-1936
Princeton subject headings:
Hegel, Georg Wilhelm Friedrich, 1770-1831.
Marx, Karl, 1818-1883.
Unamuno, Miguel de, 1864-1936.