Stone Bob. (1992). Successful direct marketing methods. NTC Bus Books.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रStone Bob. Successful Direct Marketing Methods. Chicago: NTC Bus Books, 1992.
एमएलए (9वां संस्करण) प्रशस्ति पत्रStone Bob. Successful Direct Marketing Methods. NTC Bus Books, 1992.
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