"STEVE JOBS: The Biggest Mistake Apple Made After I Left Was Focusing On Profits Instead Of Products..." by Henry Blodget, www.businessinsider.com. October 23, 2011.
Thomas Cahill (2011). “How The Irish Saved Civilization: The Untold Story of Ireland's Heroic Role from the Fall of Rome to the Rise of Medieval Europe”, p.71, Hachette UK