Albert Einstein's speech made in honor of Thomas Mann, when Mann was given the Einstein Prize given by the Jewish Forum (January 1939), as quoted in Abraham Pais "Einstein Lived Here" (p. 214), 1994.
Jeffrey H. Gitomer (1998). “Customer Satisfaction is Worthless, Customer Loyalty is Priceless: How to Make Customers Love You, Keep Them Coming Back and Tell Everyone They Know”, Bard