Columbia subject headings:
Civilization--History.
Lasaulx, Ernst von, 1805-1861.
Spengler, Oswald, 1880-1936.
Vollgraff, Karl, 1794-1863.
Harvard subject headings:
Civilization--History
Lasaulx, Ernst von, 1805-1861.
Spengler, Oswald, 1880-1936.
Vollgraff, Karl, 1794-1863.
Princeton subject headings: