Columbia subject headings:
Cardinals--History.
Catholic Church. Collegium Cardinalium--History.
Christianity and politics--Catholic Church--History.
Papacy--History.
Papal courts--History.
Popes--Election.
Harvard subject headings:
Cardinals--History.
Catholic Church. Collegium Cardinalium--History.
Christianity and politics--Catholic Church--History.
Papacy--History
Papal courts--History.
Popes--Election
Princeton subject headings: