Columbia subject headings:
Basilica di San Pietro in Vaticano. Capitolo--History--Sources.
Catholic Church--Italy--Rome--History--Sources.
Chapters, Cathedral, collegiate, etc.--History--Sources.
Chapters, Cathedral, collegiate, etc.--Vatican City--History--Sources.
Harvard subject headings:
Basilica di San Pietro in Vaticano. Capitolo--History--Sources.
Catholic Church--Italy--Rome--History--Sources.
Chapters, Cathedral, collegiate--Vatican City--History--Sources.
Princeton subject headings:
Basilica di San Pietro in Vaticano. Capitolo--History--Sources.
Catholic Church--Italy--Rome--History--Sources.
Chapters, Cathedral, collegiate, etc.--History--Sources.
Chapters, Cathedral, collegiate, etc.--Vatican City--History--Sources.