Não informado. (1975). The Bell Journal of Economics. American Telephone and Telegraph Company.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. The Bell Journal of Economics. New York: American Telephone and Telegraph Company, 1975.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. The Bell Journal of Economics. American Telephone and Telegraph Company, 1975.
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