George R. R. Martin (2012). “George R. R. Martin's A Game of Thrones 5-Book Boxed Set (Song of Ice and Fire Series): A Game of Thrones, A Clash of Kings, A Storm of Swords, A Feast for Crows, and and A Dance with Dragons”, p.192, Bantam
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