Columbia subject headings:
Kaliningrad (Kaliningradskai︠a︡ oblastʹ, Russia)--Civilization--Congresses.
Prussia (Germany)--Civilization--Congresses.
Prussia, East (Poland and Russia)--Civilization--Congresses.
Harvard subject headings:
Prussia, East (Poland and Russia)--Civilization.
Prussia, East (Poland and Russia)--History.
Princeton subject headings:
Prussia (Germany)--Civilization--History.
Prussia (Germany)--History.
Prussia, East (Poland and Russia)--Civilization--History.
Prussia, East (Poland and Russia)--History.