Columbia subject headings:
Canon law.
Gregory, Cardinal of San Crisogono, -1113.
Polycarpus (Canon law collection)
Harvard subject headings:
Canon law.
Gregory, Cardinal of San Crisogono, -1113
Polycarpus (Canon law collection)
Princeton subject headings:
Canon law.
Gregory, Cardinal of San Crisogono, -1113.
Polycarpus (Canon law collection)