Columbia subject headings:
Catholic Church--Customs and practices.
Christian art and symbolism--Medieval, 500-1500.
Popes--Heraldry--History--15th century.
Tiara, Papal--History--15th century.
Harvard subject headings:
Papacy--History--1447-1565
Papal courts--History.
Schism, The Great Western, 1378-1417.
Princeton subject headings:
Catholic Church--Customs and practices.
Christian art and symbolism--Medieval, 500-1500.
Popes--Heraldry--History.
Tiara, Papal--History.