Columbia subject headings:
Catholic Church--History--20th century--Congresses.
John XXIII, Pope, 1881-1963--Congresses.
Vatican Council (2nd : 1962-1965 : Basilica di San Pietro in Vaticano)--Congresses.
Harvard subject headings:
Vatican Council (2nd : 1962-1965 : Basilica di San Pietro in Vaticano)--Congresses.
Princeton subject headings: