Books by Emil Mersch:
The Whole Christ. The Historical Development of the Doctrine of the Mystical Body in Scripture and Tradition. Translated by John Kelly, S.J. Milwaukee, The Bruce Publishing Company, 1938. (Historical background for his Theology of the Mystical Body.)
The Theology of the Mystical Body. Translated by Cyril Vollert, S.J. St. Louis: Herder Book Co., 1951; fifth printing, 1962. (One of the great works on the theology of the central Christian mysteries.)
Le Christ, L'homme et L'universe. Prolégomènes à la théologie du corps mystique. Paris: Desclée De Brouwer. 1962. (Material left out of the published edition of The Theology of the Mystical Body.)
Aquinas, St. Thomas. Summa Theologica.
Aubert, Roger. (1950) Le Probleme de l'Acte de Foi. Publications Universitaires de Louvain. (An extensive study of the historical and theological issues surrounding the act of faith.)
Conley, Kieran. (1963) A Theology of Wisdom. Dubuque, IA: The Priory Press.
Crouzel, Henri. (1961) Origène et la "Connaissance Mystique". Desclée de Brouwer.
Guitton, Jean. (1955) The Problem of Jesus. A Free-Thinker's Diary. London: Burns & Oates. (A well-written account of why it is reasonable to believe.)
Kaiser, Robert Blair. (1985) The Politics of Sex and Religion: A Case History in the Development of Doctrine, 1962-1984. Leaven Press.
Maritain. (1969) On the Grace and Humanity of Jesus. NY: Herder and Herder.
Maritain, Raissa. (1955) "Abraham and the Ascent of Conscience" in The Bridge: A Yearbook of Judaeo-Christian Studies by John M. Oesterreicher, ed. Pantheon Books.
Noonan, John T., Jr. (1986) Contraception: A History of Its Treatment by the Catholic Theologians and Canonists. Cambridge, MA: Harvard University Press.
Scheeben, Matthias Joseph. (1946) The Mysteries of Christianity. St. Louis, MO and London: B. Herder Book Co. (Scheeben was one of the great theologians of the 19th century.)
Many of these books are, unfortunately, out of print. Try your library's interlibrary loan system to see if they can borrow them for you.