Columbia subject headings:
Castles--Germany--Osnabrück Region--Exhibitions.
Fortification--Germany--Osnabrück Region--Exhibitions.
Osnabrück Region (Germany)--Antiquities--Exhibitions.
Harvard subject headings:
Castles--Germany--Osnabrück Region--Exhibitions.
Fortification--Germany--Osnabrück Region--Exhibitions.
Osnabrück Region (Germany)--Antiquities--Exhibitions.
Princeton subject headings: