Lawrence G. Lovasik (1999). “The Hidden Power of Kindness: A Practical Handbook for Souls who Dare to Transform the World, One Deed at a Time”, p.189, Sophia Institute Press
Aeschylus (1956). “Aeschylus: The suppliant maidens, The Persians, translated by S. G. Benardete. Seven against Thebes, Prometheus bound, translated by D. Grene”