Não informado. Statistical and other data on minerals: Quarterly information circular. Republic of South Africa, Department of Mines.
Παραπομπή σε μορφή Chicago (17η εκδ.)Não informado. Statistical and Other Data on Minerals: Quarterly Information Circular. Pretoria, Africa do Sul: Republic of South Africa, Department of Mines.
Παραπομπή σε μορφή MLA (8th εκδ.)Não informado. Statistical and Other Data on Minerals: Quarterly Information Circular. Republic of South Africa, Department of Mines.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.