Columbia subject headings:
Harvard subject headings:
Frederick I, Holy Roman Emperor, approximately 1123-1190--Congresses.
Germany--History--Frederick I, 1152-1190--Congresses.
Germany--Kings and rulers--Biography--Congresses.
Princeton subject headings:
Frederick I, Holy Roman Emperor, approximately 1123-1190--Congresses.
Holy Roman Empire--History--Frederick I, 1152-1190--Congresses.