Sewell Carl. (1990). Customers for Life: How to turn that one-time buyer into a lifetime customer. Pocket Books Publishing.
Chicago-referens (17:e uppl.)Sewell Carl. Customers for Life: How to Turn That One-time Buyer into a Lifetime Customer. NewYok: Pocket Books Publishing, 1990.
MLA-referens (9:e uppl.)Sewell Carl. Customers for Life: How to Turn That One-time Buyer into a Lifetime Customer. Pocket Books Publishing, 1990.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.