Columbia subject headings:
Canossa (Castle)
Gregory VII, Pope, approximately 1015-1085.
Henry IV, Holy Roman Emperor, 1050-1106.
Harvard subject headings:
Canossa (Castle)
Church history--11th century.
Church history--Middle Ages, 600-1500
Civilization, Medieval
Gregory VII, Pope, approximately 1015-1085
Henry IV, Holy Roman Emperor, 1050-1106.
Princeton subject headings: