Sewell, C. (2002). Customers for Life (1st.). Crown Business.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रSewell, Carl. Customers for Life. 1st. Crown Business, 2002.
एमएलए (9वां संस्करण) प्रशस्ति पत्रSewell, Carl. Customers for Life. 1st. Crown Business, 2002.
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