Não informado. (1956). Journal of the Southern African Institute of Mining and Metallurgy. South African Institute of Mining and Metallurgy.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रNão informado. Journal of the Southern African Institute of Mining and Metallurgy. Johannesburg, Africa do Sul: South African Institute of Mining and Metallurgy, 1956.
एमएलए (8वां संस्करण) प्रशस्ति पत्रNão informado. Journal of the Southern African Institute of Mining and Metallurgy. South African Institute of Mining and Metallurgy, 1956.
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