by M. R. Johnson and F. G. Le RouxRepublic of South Africa, Dept. of Mineral and Energy Affairs, Geological Survey : Obtainable from the Govt. Printerc1994
by N. Keyser and C.P. Du PlessisRepublic of South Africa, Dept. of Mineral and Energy Affairs, Geological Survey : Obtainable from the Govt. Printerc1993