HG Wells, Rudy Rucker, Colin Wilson (2013). “The Last Books of H.G. Wells: The Happy Turning: A Dream of Life & Mind at the End of its Tether”, p.25, Monkfish Book Publishing
Stephen R. Covey (1994). “Daily Reflections for Highly Effective People: Living THE SEVEN HABITS OF HIGHLY SUCCESSFUL PEOPLE Every Day”, p.273, Simon and Schuster