Columbia subject headings:
Harvard subject headings:
Germany--History--Frederick I, 1152-1190.
Henry, Duke of Saxony, 1129-1195.
Princes--Germany--Biography
Princes--Germany--Biography.
Princeton subject headings:
Germany--History--Frederick I, 1152-1190.
Henry, Duke of Saxony, 1129-1195.
Princes--Germany--Biography.