Deeper Reading: Theology and Philosophy

The 1909 Catholic Encyclopedia

The Early Church Fathers, originally a 38 volume set edited by Philip Schaff, et. al. Commentaries/notes are from a reformed perspective

The Early Church Fathers - Additional Texts, texts not included in the above.

Works of St. Thomas Aquinas in English

The Enneads, by Plotinus (Πλωτίνος), leading Neoplatonist philosopher, who, though not Christian, influenced Christian thought throughout the centuries.

Works by Plato

Works by Aristotle