Birth control: a statement of Christian doctrine against the Neo-Malthusians, by Sutherland, Halliday (New York : P. J. Kenedy & sons, 1922). Available at Manybooks.net, Internet Archive and Open Library. Apologetics, Bioethics, Ethics, Morals.
The Christian Father; what he should be, and what he should do, together with a collection of prayers suitable to his condition, by Right Rev. W. Cramer, Bishop of Munster, translated by Rev. L.A. Lambert (New York: Benziger Brothers, 1883). With Imprimatur. Available on Internet Archive and Open Library. [NB, Both of the Internet Archive and Open Library entries mistakenly index the book as Lives of the popes in the early middle ages, by Horace Kinder Mann, Johannes Hollnsteiner, but the document links lead to The Christian Father. I’ll check it every now and then to see if the index is modified.]
Compendium of the Social Doctrine of the Church, by the Pontifical Council for Justice and Peace. Available at the Holy See.
Dignitas Connubii: Instruction to be Observed by Diocesan and Interdiocesan Tribunals in Handling Causes of the Nullity of Marriage, by the Pontifical Council for Legislative Texts, January 25, 2005. Available at the Holy See and JGray.org.
Essay on Love, by Ernest R. Hull, S.J. (Bombay: Examiner Press; St. Louis, Mo.: B. Herder; etc., 1912). Available at Internet Archive and Open Library.
The Law of Christian Marriage According to the Teaching and Discipline of the Catholic Church, by Arthur Devine (London: Washbourne, 1908). With Imprimatur. Available on Internet Archive and Open Library (Digitizing sponsor: MSN; Book contributor: Kelly Library, University of Toronto).
Living Tradition: Organ of the Roman Theological Forum, no. 43 (September-November 1992). Contains “The Ex Cathedra Status of the Encyclical Humanae Vitae”, by Brian W. Harrison. Available at the Roman Theological Forum..
Ne Temere: Decree concerning betrothal and marriage, by the Sacred Congregation of the Council, August 10, 1907. May be read online at the EWTN Library.
Pastoral letter of the Archbishops and Bishops of the United States Assembled in Conference at the Catholic University of America, September, 1919 (Washington, D.C., The National Catholic Welfare Council, 1920). Available at Open Library and Internet Archive, with a 2nd copy here. [This is a restatement of doctrine and an exhortation on all aspects of the Catholic life in the United States.]
Pope John Paul II’s Theology of the Body. A tract that summarizes the theology of the body with representative excerpts of the Pope’s lectures/addresses. Indexed on JP2Info.
Theology of the Body, by Pope John Paul II. Weekly Audiences on the subject of the Redemption of the Body and the Sacramentality of Marriage, September 5, 1979 – November 28, 1984. May be downloaded in PDF format from this webpage of Catholic Primer. May be read on Catechetics Online and on EWTN,