Church Documents
Pope Pius X, Tra le Sollecitudini, Motu Proprio Promulgated November 22, 1903: https://adoremus.org/1903/11/22/tra-le-sollecitudini/
Second Vatican Ecumenical Council, constitution on the Sacred Liturgy, Sacrosanctum Concilium, Promulgated by Pope Paul VI December 4, 1963 (especially chapter 6): http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_const_19631204_sacrosanctum-concilium_en.html
Second Vatican Ecumenical Council, Musicam Sacram, Instruction on Music in the Liturgy, 5 March, 1967: http://www.vatican.va/archive/hist_councils/ii_vatican_council/documents/vat-ii_instr_19670305_musicam-sacram_en.html
Pope John Paul II, Chirograph For the Centenary Of the Motu Proprio “Tra Le Sollecitudini,” On Sacred Music, November 22, 2003: http://w2.vatican.va/content/john-paul-ii/en/letters/2003/documents/hf_jp-ii_let_20031203_musica-sacra.html
Pope Benedict XVI, Post Synodal Apostolic Exhortation Sacramentum Caritatis, signed February 22, 2007: http://w2.vatican.va/content/benedict-xvi/en/apost_exhortations/documents/hf_ben-xvi_exh_20070222_sacramentum-caritatis.html
Pope Benedict XVI, Summorum Pontificum, Motu Proprio Promulgated July 2007: https://w2.vatican.va/content/benedict-xvi/en/motu_proprio/documents/hf_ben-xvi_motu-proprio_20070707_summorum-pontificum.html
Books on Sacred Music
Joseph Swain, Sacred Treasure, Liturgical Press (June 30, 2012): https://litpress.org/Products/6255/Sacred-Treasure
Edward Schaefer, Catholic Music Through the Ages, Liturgy Training Publications (September 15, 2008): https://www.amazon.com/Catholic-Music-through-Ages-Worshipping/dp/1595250204
Robert Hayburn, Papal Legislation on Sacred Music 95 A.D. to 1977 A.D, 1979: https://www.amazon.com/Papal-Legislation-Sacred-Music-1977/dp/0814610129
William Peter Mahrt, The Musical Shape of the Liturgy, Church Music Association of America, (2012). The Musical Shape of the Liturgy
Books on the Sacred Liturgy
Joseph Cardinal Ratzinger, The Spirit of the Liturgy, Ignatius Press (August 26, 2014): https://www.ignatius.com/The-Spirit-of-the-Liturgy-P2310.aspx
Romano Guardini, The Spirit of the Liturgy, 1918. https://www.amazon.com/Spirit-Liturgy-Milestones-Catholic-Theology/dp/0824517776
Dom Alcuin Reid, The Organic Development of the Liturgy, Ignatius Press (2005): https://www.amazon.com/Organic-Development-Liturgy-Principles-Twentieth-Century/dp/1586171062
Aidan Nichols, OSB, Rome and the Eastern Churches, Ignatius Press (March 4, 2010): https://www.ignatius.com/Rome-and-the-Eastern-Churches-P2067.aspx
Helpful Articles
Joseph Cardinal Ratzinger, Address on the New Evangelization, December 12, 2000: https://www.ewtn.com/new_evangelization/Ratzinger.htm
Robert Cardinal Sarah, Address on the 10th Anniversary of “Summorum Pontificum,” March 29, 2017. https://www.catholicworldreport.com/2017/03/31/cardinal-sarahs-address-on-the-10th-anniversary-of-summorum-pontificum/
Robert Cardinal Sarah, From the Silence of the Soul United With Christ To the Silence of God in His Glory, Address to “Pro Liturgia” Assembly, October 20, 2018. https://www.catholicculture.org/culture/library/view.cfm?recnum=12003
Francis Cardinal Arinze, Latin and Vernacular, Keynote Address at the Gateway Liturgical Conference in St. Louis, Missouri 11 November 2006. https://www.ewtn.com/library/Liturgy/latinvernac.htm
Monsignor Andrew Wadsworth, “Towards the Future: Singing the Mass,” Keynote Address at the Southeastern Liturgical Music Symposium, August 21, 2010: http://www.newliturgicalmovement.org/2010/08/towards-future-singing-mass-by-msgr.html#.XHakcIhKiUk
Pope Benedict XVI: Preface to the Russian Edition of his works. https://rorate-caeli.blogspot.com/2017/04/exclusive-text-by-benedict-xvi-crisis.html
Paul Jernberg, “The Logos of Sacred Music,” June 5th, 2012. https://www.catholicculture.org/commentary/articles.cfm?id=535
Further Helpful Reading
Although these books are not primarily about the Liturgy or liturgical music, we highly recommend them for their insights into the spiritual dimension of the Liturgy and its sacred music!
Robert Cardinal Sarah, The Power of Silence: Against the Dictatorship of Noise, Ignatius Press, (April 15, 2017). The Power of Silence
Robert Cardinal Sarah, God or Nothing, Ignatius Press, (September 1, 2015). God or Nothing