Edward Gibbon, J. B. Bury (2013). “The History of the Decline and Fall of the Roman Empire: Edited in Seven Volumes with Introduction, Notes, Appendices, and Index”, p.257, Cambridge University Press
Edward Gibbon (2016). “THE HISTORY OF THE DECLINE AND FALL OF THE ROMAN EMPIRE (All 6 Volumes): From the Height of the Roman Empire, the Age of Trajan and the Antonines - to the Fall of Byzantium; Including a Review of the Crusades, and the State of Rome during the Middle Ages”, p.3284, e-artnow
Hillary Clinton's speech at the Clinton-Sanders Democratic presidential debate in Durham, New Hampshire, hosted by MSNBC, www.nytimes.com. February 4, 2016.
Dr. Dan Ariely (2010). “The Upside of Irrationality (Enhanced Edition): The Unexpected Benefits of Defying Logic at Work and at Home”, p.29, Harper Collins