Columbia subject headings:
Church history--Middle Ages, 600-1500.
Du Boulay, F. R. H.
Europe--Church history--600-1500.
Middle Ages.
Harvard subject headings:
Church history--Middle Ages, 600-1500
Du Boulay, F. R. H.
Europe--Church history--600-1500.
Middle Ages.
Princeton subject headings:
Church history--Middle Ages, 600-1500.
Du Boulay, F. R. H.
Europe--Church history--600-1500.
Middle Ages.