Columbia subject headings:
Church history--11th century.
Gregory VII, Pope, approximately 1015-1085.
Otto I, Bishop of Freising, -1158.
Harvard subject headings:
Church history--11th century.
Gregory VII, Pope, approximately 1015-1085
Princeton subject headings:
Church history--11th century.
Gregory VII, Pope, approximately 1015-1085.
Otto I, Bishop of Freising, -1158.