Paul VI, P. (1966). On liturgy in choir duty: Letter of Pope Paul VI to superiors general of clerical religious institutes bound by the obligation of choir duty. National Catholic Welfare Conference.
Trích dẫn kiểu Chicago (xuất bản lần thứ 7)Paul VI, Pope. On Liturgy in Choir Duty: Letter of Pope Paul VI to Superiors General of Clerical Religious Institutes Bound by the Obligation of Choir Duty. Washington, D.C.: National Catholic Welfare Conference, 1966.
Trích dẫn kiểu MLA (xuất bản lần thứ 8)Paul VI, Pope. On Liturgy in Choir Duty: Letter of Pope Paul VI to Superiors General of Clerical Religious Institutes Bound by the Obligation of Choir Duty. National Catholic Welfare Conference, 1966.
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