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
Jeffrey Gitomer (2018). “Jeffrey Gitomer's Little Gold Book of YES! Attitude: New Edition, Updated & Revised: How to Find, Build and Keep a YES! Attitude for a Lifetime of SUCCESS & HAPPINESS”, p.62, Sound Wisdom
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