Columbia subject headings:
Frederick I, Holy Roman Emperor, approximately 1123-1190.
Lombardy (Italy)--History--Sources.
Harvard subject headings:
Frederick I, Holy Roman Emperor, approximately 1123-1190.
Lombardy (Italy)--History--Sources.
Princeton subject headings:
Frederick I, Holy Roman Emperor, approximately 1123-1190.
Lombardy (Italy)--History--Sources.