Manly P. Hall (2010). “The Secret Teachings of All Ages: An Encyclopedic Outline of Masonic, Hermetic, Qabbalistic and Rosicrucian Symbolical Philosophy”, p.36, Courier Corporation
William Butler Yeats, Richard J. Finneran, George Bornstein (2007). “The Collected Works of W.B. Yeats Volume IV: Early Essays”, p.88, Simon and Schuster