Columbia subject headings:
Bulgars (Turkic people)--Russia (Federation)--Tatarstan--History.
Tatarstan (Russia)--History.
Harvard subject headings:
Bulgars (Turkic people)--Russia (Federation)--Tatarstan--History.
Tatarstan (Russia)--History.
Princeton subject headings:
Bulgars (Turkic people)--History.
Volga River Region (Russia)--History.