Edgar Mitchell (2009). “The Way of the Explorer: An Apollo Astronaut's Journey Through the Material and Mystical Worlds: Easyread Large Bold Edition”, p.454, ReadHowYouWant.com
John Milton (1824). “The Poetical Works of John Milton: With Notes of Various Authors, Principally from the Edition of Thomas Newton, Charles Dunster, and Thomas Warton, to which is Prefixed, Newton's Life of Milton”, p.368