Online sources for the material from Aristotle and Aquinas:
- Aristotle, Nicomachean Ethics, Book III, Ch. 1. Marginal page numbers 1752 - 54.
- Aquinas, Summa Theologiae
- First Part of the Second Part, Question 6, "Of the Voluntary and the Involuntary"
- First Part, Question 83, "Of Free Will" – Note that this translation uses "free will" where ours uses "free choice."
- First Part of the Second Part, Question 13, "Of Choice, Which Is an Act of the Will with Regard to the Means"
- First Part of the Second Part, Question 14, "Of Counsel, Which Precedes Choice"
Online sources for material from Hume:
- Hume, Enquiry Concerning Human Understanding, Section 8, "Of Liberty and Necessity"
- Hume, Treatise of Human Nature, Book II, Part III, Section iii, "Of the Influencing Motives of the Will"