Medieval Trinitarian Theology (Texts):
Augustine, De Trinitate (Nicene and Post-Nicene Fathers series edition)
Boethius, De Trinitate (Loeb edition)
Anselm, De Incarnatione Verbi (Jasper Hopkins translation)
Anselm, De Processione Spiritus Sancti (Jasper Hopkins translation)
Anselm, Monologion (Jasper Hopkins translation)
Aquinas, Summa Theologiae, part 1, question 40 (New Advent version)
Henry of Ghent, Summa Quaestionum Ordinariarum, article 56 (My translation)
Scotus, Ordinatio, book 1, distinction 26 (My translation)
Ockham_Sentences, book 1, distinction 26 (My translation)

Other:
Avicenna_Meta.9.4.pdf (My translation, with the Latin text)