Columbia subject headings:
Harvard subject headings:
Berdi︠a︡ev, Nikolaĭ, 1874-1948
Bulgakov, Sergiĭ, 1871-1944.
Frank, S. L. (Semen Li︠u︡dvigovich), 1877-1950
Philosophy, Russian--19th century.
Philosophy, Russian--20th century.
Philosophy, Russian--Religious aspects.
Socialism--Russia.
Socialism--Soviet Union
Princeton subject headings:
Berdi︠a︡ev, Nikolaĭ, 1874-1948.
Bulgakov, Sergiĭ, 1871-1944.
Frank, S. L. (Semen Li︠u︡dvigovich), 1877-1950.
Philosophy, Russian--19th century.
Philosophy, Russian--20th century.
Philosophy, Russian--Religious aspects.
Socialism--Russia.
Socialism--Soviet Union.