Columbia subject headings:
Denmark--Kings and rulers.
Oldenburg, House of.
Harvard subject headings:
Denmark--Kings and rulers.
Europe, Northern--Kings and rulers.
Oldenburg (Grafschaft)--History.
Oldenburg, House of.
Princeton subject headings:
Denmark--Kings and rulers.
Europe, Northern--Kings and rulers.
Oldenburg (Grafschaft)--History.
Oldenburg, House of.