Ethics and Natural Law:

50 Questions on the Natural Law by Charles Rice

A Course in Thomistic Ethics by D.Q. McInerny

After the Natural Law by John Lawrence Hill

Architects of the Culture of Death by Donald De Marco
& Benjamin Wiker

Aristotle: Nicomachean Ethics translated by David Ross

Christian Ethics by D. Stephen Long

The Collected Works of Jacques Maritain translated by Otto Bird 

Conscience and its Enemies by Robert P. George

Commentary on Aristotle's Nicomachean Ethics translated by C.J. Litzinger, OP 
 

Dis-Orientation, edited by John Zmirak

Ethics: The Drama of the Moral Life by Piotr Jaroszynski & Mat Anderson

Fides et Ratio by St John Paul II

The First Grace by Russell Hittinger

The Four Cardinal Virtues by Josef Pieper

Freedom and Purpose by Robert Gascoigne

Healing The Culture by Robert J. Spitzer, S.J., Ph.D.

The Idea of Natural Rights by Brian Tierney

Ideas Have Consequences by Richard M. Weaver

Integral Humanism: Freedom in the Modern World, and A Letter on Independence by Jacques Maritain

Intellectual Appetite by Paul J. Griffiths

Natural & Divine Law by Jean Porter

Natural Law by David Haines & Andrew A. Fulford

Natural Law: Reflections on Theory & Practice by Jacques Maritain 

Natural Law & Moral Inquiry by Germain Grisez

Old Errors and New Labels by Fulton J. Sheen

The Science of Correct Thinking by Celestine Bittle

Socratic Logic by Peter Kreeft

The Ten Commandments by Dr. Laura Schlessinger

Ten Universal Principles by Robert J. Spitzer, S.J., Ph.D.

Veritatis Splendor by St. John Paul II

Virtue's Splendor by Thomas S. Hibbs

​Virtuous Leadership by Alexandre Havard

What’s Wrong With the World by G.K. Chesterton 

What We Can't Not Know, by J. Budziszewski

Natural Law Philosophy:

An Inquiry Into The Human Mind, On The Principles Of Common Sense 

by Thomas Reid

The Basic Works of Aristotle edited by Richard McKeon

The Difference of Man and the Difference It Makes by Mortimer J. Adler

The Domain of Being by Celestine Bittle

The Elements of Philosophy by William Wallace, OP

Epistemology by DQ McInerny

The History of Ethics Vol. I-II by Vernon J. Bourke

The One and the Many by W. Norris Clarke, S.J.

The Philosophy of Knowledge by Kenneth T. Gallagher

Philosophical Psychology by D.Q. McInerny

Metaphysics by D.Q. McInerny