Columbia subject headings:
Celibacy--Catholic Church--History.
Church history--11th century.
Harvard subject headings:
Celibacy--Catholic Church--History.
Church history--11th century.
Princeton subject headings:
Catholic Church--Clergy--History.
Celibacy--Catholic Church--History of doctrines--Middle Ages, 600-1500.
Marriage--Religious aspects--Catholic Church--History of doctrines--Middle Ages, 600-1500.