Columbia subject headings:
Christian union.
Vatican Council (2nd : 1962-1965 : Basilica di San Pietro in Vaticano)
Harvard subject headings:
Christian union.
Vatican Council (2nd : 1962-1965 : Basilica di San Pietro in Vaticano)
Princeton subject headings:
Christian union.
Vatican Council (2nd : 1962-1965 : Basilica di San Pietro in Vaticano)