A: Sources

Alan of Lille, The Plaint of Nature (De Planctu Naturae), trans. James J. Sheridan, (Toronto: Pontifical Institute of Medieaval Studies, 1980): see an older translation of The Plaint of Nature, [At Medieval Sourcebook]
Bachelor Jr. E., Homosexuality and Ethics, (New York: Pilgrim Press, 1980) Excerpts from authors from Plato to modern times on ethical issues
Baudri de Bourgueil, Les Oeuvres poetiques de Baudri de Bourgueil, ed. Phyllis Abrahams, (Paris: Librarie Ancienne Honore Champion, 1926) (repr; Geneva, Slatkine Reprints, 1974)
St. Bernadino of Siena, Le prediche volgari, ed. Piero Bargellini, (Milan: Rizzoli, 1936)
Included two visicious vernacular anti-homosexual sermons by this 15th century saint, #35 (795-97), and #39 (893-919). Other references in his Latin works, sermons 11 and 15 in Opera Omnia, (Florence: 1950)
Bieler, Ludwig, The Irish Penitentials, (Dublin: Dublin Institute for Advanced Studies, 1963)
Includes Latin text. Homosexuality pp. 66-67. Does not translate parts he seems to consider vulgar.
Dante Alighieri, The Divine Comedy, trans. John A. Carlyle, Thomas Okey & P.H. Wicksteed, (New York: Random House, 1950; original publication details not given)
Inferno Cantos xi, xiv, xv, and Purgatorio xxvi all possibly deal with sodomy.
Francis, W.Nelson, ed., The Book of Vices and Virtues, Early English Text Society Vol 217, (London: Oxford UP, 1942)
Edited from 3 extant texts of the French of Lorens d'Orleans Somme Le Roi - a vernacular penitential. Homosexuality p.43)
Goodich, Michael, The Unmentionable Vice: Homosexuality in the Late Medieval Period, (Santa Barbara, Ca.: ABC-Clio, 1979)
Includes a 30-page translation/extract from inquisition records of Jacques Fournier in the 13th century.
Mansi, J.D.: Sacrum Conciliorum Nova et Amplissima Collectio, (Florence & Venice: 1759-1798)
Peter Damian, Liber Gomorrhanius in MPL 145, cols. 159190, and as Book of Gomorrah: An Eleventh Century Treatise Against Clerical Homosexual Practice, trans. Pierre J. Payer, (Waterloo, Ont.: Wilfred Laurier University Press, 1982)
One of the strongest attacks in the middle ages on homosexuality. The only surviving one it seems.
Stehling, Thomas, trans., Medieval Latin Poems of Male Love and Friendship, (New York: Garland, 1984)
Gay medieval literature from the Roman Empire to 1300. Alcuin, Ausonius, Luxorius, Abelard, Baudri or Bourgueil, Hilderbert of Lauardin.
McNeill, John & Helena Gamer, Medieval Handbooks of Penance: A Translation of the Principal "libri poenitentatles" and Selections from Related Documents, (New York: Columbia UP, 1938)
Does not give Latin texts.
Thomas Aquinas, Summa Theologiae, (New York & London: Blackfriars with McGraw-Hill & Eyre and Spottiswoode, 1968)
On sodomy 2.2.154.12. Aquinas rates it worse than fornication, incest or rape, but better than bestiality.