Columbia subject headings:
Bolgar Velikiy, Soviet Union--Antiquities.
Bulgarians--Russia (Federation)--Volga River Valley.
Tatars--Russia (Federation)--Volga River Valley.
Harvard subject headings:
Bulgar (Extinct City)--Antiquities.
Bulgarians--Volga River Valley (Russia).
Tatars in the Volga Valley.
Princeton subject headings:
Bulgar (Extinct city)--Antiquities.
Bulgarians in the Volga Valley.
Tatars in the Volga Valley.