Columbia subject headings:
Harvard subject headings:
Fortification--Kaliningrad (Kaliningradskai︠a︡ oblastʹ, Russia)
Kaliningrad (Kaliningradskai︠a︡ oblastʹ, Russia)--History, Military.
Princeton subject headings:
Fortification--Kaliningrad (Kaliningradskai︠a︡ oblastʹ, Russia).
Kaliningrad (Kaliningradskai︠a︡ oblastʹ, Russia)--History, Military.