What has the author Desmond A Pretorius written?

Desmond A. Pretorius has written:

'The EGRU information circulars' -- subject(s): Bibliography, Geology, University of the Witwatersrand, University of the Witwatersrand. Economic Geology Research Unit

'The role of E.G.R.U. in mineral exploration in South Africa' -- subject(s): Mines and mineral resources, Prospecting, University of the Witwatersrand, University of the Witwatersrand. Economic Geology Research Unit