Catholic Church. Pope (1963-1978 : Paul VI) & Higgins, G. G. (1971). Apostolic letter of His Holiness Pope Paul VI to Cardinal Maurice Roy, president of the Council of the Laity and of the Pontifical Commission Justice and Peace, on the occasion of the eightieth anniversary of the encyclical Rerum novarum, May 14, 1971. United States Catholic Conference.
Παραπομπή σε μορφή Chicago (17η εκδ.)Catholic Church. Pope (1963-1978 : Paul VI) και George G. Higgins. Apostolic Letter of His Holiness Pope Paul VI to Cardinal Maurice Roy, President of the Council of the Laity and of the Pontifical Commission Justice and Peace, on the Occasion of the Eightieth Anniversary of the Encyclical Rerum Novarum, May 14, 1971. Washington, D. C.: United States Catholic Conference, 1971.
Παραπομπή σε μορφή MLA (8th εκδ.)Catholic Church. Pope (1963-1978 : Paul VI) και George G. Higgins. Apostolic Letter of His Holiness Pope Paul VI to Cardinal Maurice Roy, President of the Council of the Laity and of the Pontifical Commission Justice and Peace, on the Occasion of the Eightieth Anniversary of the Encyclical Rerum Novarum, May 14, 1971. United States Catholic Conference, 1971.