Columbia subject headings:
Opochka (Russia)--History--16th century.
Russia--History, Military--16th century.
Russia--History--To 1533.
Harvard subject headings:
Opochka (Russia)--History--16th century.
Russia--History, Military--To 1801.
Russia--History--To 1533.
Princeton subject headings:
Opochka (Russia)--History--16th century.
Russia--History, Military--16th century.
Russia--History--To 1533.