Socrates, Plato, Aristotle (1967). “Wit and Wisdom of Socrates, Plato, Aristotle: Being a Treasury of Thousands of Glorious, Inspiring and Imperishable Thoughts, Views and Observations of the Three Great Greek Philosophers, Classified Under about Four Hundred Subjects for Comparative Study”
Plato (2013). “The Republic: A Socratic Dialogue Concerning the Definition of Justice and the Order and Character of the Just City-State and the Just Man (Beloved Books Edition)”, p.322, Lulu Press, Inc
Marcus Aurelius, Epictetus, Lucius Annaeus Seneca (2015). “Stoic Six Pack: Meditations of Marcus Aurelius The Golden Sayings Fragments and Discourses of Epictetus Letters from a Stoic and The Enchiridion”, p.39, Lulu.com