Sewell Carl. (1990). Customers for Life: How to turn that one-time buyer into a lifetime customer. Pocket Books Publishing.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSewell Carl. Customers for Life: How to Turn That One-time Buyer into a Lifetime Customer. NewYok: Pocket Books Publishing, 1990.
एमएलए (9वां संस्करण) प्रशस्ति पत्रSewell Carl. Customers for Life: How to Turn That One-time Buyer into a Lifetime Customer. Pocket Books Publishing, 1990.
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