Columbia subject headings:
Love--Religious aspects--Christianity--History of doctrines--Middle Ages, 600-1500.
Marriage--Religious aspects--Catholic Church.
Harvard subject headings:
Love--Religious aspects--Christianity--History of doctrines--Middle Ages, 600-1500.
Marriage--Religious aspects--Catholic Church--History.
Princeton subject headings:
Catholic Church.
Love--Religious aspects--Catholic Church--History of doctrines.
Marriage--Religious aspects--Catholic Church.