Columbia subject headings:
Church history--Middle Ages, 600-1500.
Grevs, I. M. (Ivan Mikhaĭlovich), 1860-1941.
Middle Ages.
Rome (Italy)--History.
Harvard subject headings:
Church history--Middle Ages, 600-1500
Grevs, I. M. (Ivan Mikhaĭlovich), 1860-1941.
Middle Ages
Rome--History
Princeton subject headings: