Columbia subject headings:
Harvard subject headings:
Germany--Kings and rulers--Biography.
Hohenzollern-Sigmaringen, House of.
Holy Roman Empire--Kings and rulers--Biography.
Royal houses--Europe--History.
Princeton subject headings:
Germany--Kings and rulers--Biography.
Hohenzollern-Sigmaringen, House of.
Holy Roman Empire--Kings and rulers--Biography.
Royal houses--Europe--History.