Columbia subject headings:
Permskai︠a︡ oblastʹ (Russia)--Economic conditions--Sources.
Working class--Russia (Federation)--Permskai︠a︡ oblastʹ.
Harvard subject headings:
Industries--Russia (Federation)--Permskai︠a︡ oblastʹ--History--Sources.
Working class--Russia (Federation)--Permskai͡a oblastʹ--History--Sources.
Working class--Russia--Permskai︠a︡ oblastʹ--History--Sources.
Princeton subject headings: