Columbia subject headings:
Bulgakov, S. N. (Sergeĭ Nikolaevich)
Church--History of doctrines--20th century.
Harvard subject headings:
Bulgakov, Sergiĭ, 1871-1944.
Church--Authority
Princeton subject headings:
Bulgakov, Sergiĭ, 1871-1944.
Church--History of doctrines--20th century.