Aquinas: Basic Works

The Arrogance of Humanism

Luther and Calvin on Secular Authority

Treatise on Law

On Law, Morality, and Politics: Edition 2

Summa Theologica (All Complete & Unabridged 3 Parts + Supplement & Appendix + interactive links and annotations)

Medieval Philosophy: A Very Short Introduction

Philosophy in the Middle Ages: The Christian, Islamic, and Jewish Traditions, Edition 3

Questions on Love and Charity: Summa Theologiae, Secunda Secundae, Questions 23–46

Philovesophy

Commentary on Aristotle's Politics

On Evil

Dream of Reason: A History of Western Philosophy from the Greeks to the Renaissance (New Edition)

The Treatise on the Divine Nature: Summa Theologiae I 1-13

Maimonides: Life and Thought

SUMMA THEOLOGICA: Including supplement, appendix, interactive links and annotations

Simon of Genoa's Medical Lexicon

The Treatise on Human Nature: Summa Theologiae 1a 75-89

Monologion and Proslogion: with the replies of Gaunilo and Anselm