Não informado. (1973). International petroleum abstracts. Institute of Petroleum.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. International Petroleum Abstracts. London: Institute of Petroleum, 1973.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. International Petroleum Abstracts. Institute of Petroleum, 1973.
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