Columbia subject headings:
Bulgakov, Sergiĭ, 1871-1944.
Idealism.
Philosophy, Russian--20th century.
Problemy idealizma.
Socialism.
Struve, Petr Berngardovich, 1870-1944.
Terrorism.
Harvard subject headings:
Bulgakov, Sergiĭ, 1871-1944.
Idealism.
Philosophy, Russian--20th century.
Socialism.
Struve, Petr Berngardovich, 1870-1944.
Terrorism.
Princeton subject headings:
Bulgakov, Sergiĭ, 1871-1944.
Idealism.
Philosophy, Russian--20th century.
Problemy idealizma.
Socialism.
Struve, Petr Berngardovich, 1870-1944.
Terrorism.