Não informado. (1970). Working paper series. National Bureau of Economic Research.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Working Paper Series. Cambridge, Mass: National Bureau of Economic Research, 1970.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Working Paper Series. National Bureau of Economic Research, 1970.
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