Kurt Vonnegut (2016). “If This Isn't Nice What Is? (Much) Expanded Second Edition: The Graduation Speeches and Other Words to Live By”, p.131, RosettaBooks
George Carlin (2015). “3 x Carlin: An Orgy of George including Brain Droppings, Napalm and Silly Putty, and When Will Jesus Bring the Pork Chops?”, p.205, Hachette UK
"Various techniques used in connection with random digits" by John von Neumann in "Monte Carlo Method" edited by A.S. Householder, G.E. Forsythe and H.H. Germond, 1951.