Columbia subject headings:
Harvard subject headings:
Church history--11th century.
Gregory VII, Pope, approximately 1015-1085
Italy--Church history--Middle Ages, 600-1500.
Peter Damian, Saint, 1007?-1072.
Reformation--Early movements
Princeton subject headings:
Canon law--History.
Church history--11th century.
Church renewal--Catholic Church--History.
Church renewal--Europe--History.
Church renewal--History of doctrines.
Gregory VII, Pope, approximately 1015-1085.
Peter Damian, Saint, 1007?-1072.