Não informado. (1971). Industrial Development Abstracts. United Nations, Industrial Development Organization.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Industrial Development Abstracts. New York: United Nations, Industrial Development Organization, 1971.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Industrial Development Abstracts. United Nations, Industrial Development Organization, 1971.
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