Não informado. (1989). Minerals Industry International. Institution of Mining and Metallurgy.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Minerals Industry International. London: Institution of Mining and Metallurgy, 1989.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Minerals Industry International. Institution of Mining and Metallurgy, 1989.
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