Columbia subject headings:
Ermak, -1585.
Siberia (Russia)--Discovery and exploration--Russian.
Harvard subject headings:
Ermak, -1585--Journeys--Russia (Federation)--Siberia.
Ermak, -1585--Travel--Russia (Federation)--Siberia.
Siberia (Russia)--Discovery and exploration.
Princeton subject headings:
Ermak, -1585.
Siberia (Russia)--History.