Columbia subject headings:
Ural Mountains Region (Russia)--History.
Volga River Region (Russia)--History.
Harvard subject headings:
Labor and laboring classes--Russia (Federation)--Volga River Valley.
Labor--Russia (Federation)--Volga River Valley.
Socialism--Russia (Federation)--Volga River Valley.
Volga River Valley (Russia)--History--Sources.
Working class--Russia (Federation)--Volga River Valley.
Princeton subject headings:
Ural Mountains Region (Russia)--History.
Volga River Valley (Russia)--History.