Robert Spector, Patrick D. McCarthy (2012). “The Nordstrom Way to Customer Service Excellence: The Handbook For Becoming the "Nordstrom" of Your Industry”, p.9, John Wiley & Sons
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