Columbia subject headings:
Harvard subject headings:
Geology, Stratigraphic--Precambrian
Geology--South Africa--Witwatersrand Region.
Gold mines and mining--South Africa--Witwatersrand Region.
Princeton subject headings:
Geology, Stratigraphic--Precambrian.
Geology--South Africa--Witwatersrand.
Gold ores--South Africa--Witwatersrand.