Visser, D.J.L. 1984. Geological map of the Republics of South Africa, Transkei, Bophuthatswana, Venda and Ciskei and the Kingdoms of Lesotho and Swaziland. Government Printer, Pretoria.
http://pza.sanbi.org/references/visser-djl-1984-geological-map-republics-south-africa-transkei-bophuthatswana-venda-and