Não informado. (2001). The Bell System Technical Journal. American Telephone and Telegraph Company.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. The Bell System Technical Journal. New York: American Telephone and Telegraph Company, 2001.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. The Bell System Technical Journal. American Telephone and Telegraph Company, 2001.
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