Viljoen, V. E. (1962). The mineralogy and gensis of the Mangula, Vaalwater and Umkondo ore deposits. [University of Stellenbosch].
Lua i Stíl Chicago (17ú heag.)Viljoen, V. E. The Mineralogy and Gensis of the Mangula, Vaalwater and Umkondo Ore Deposits. Stellenbosch: [University of Stellenbosch], 1962.
Lua MLA (8ú heag.)Viljoen, V. E. The Mineralogy and Gensis of the Mangula, Vaalwater and Umkondo Ore Deposits. [University of Stellenbosch], 1962.
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