Não informado. (1960). Information Circular. University of the Witwatersrand, Economic Geology Research Unit.
Chicago-viite (17. p.)Não informado. Information Circular. Johannesburg, Africa do Sul: University of the Witwatersrand, Economic Geology Research Unit, 1960.
MLA-viite (8. p.)Não informado. Information Circular. University of the Witwatersrand, Economic Geology Research Unit, 1960.
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