Marasas, Walter F.O. (Walter Friedrich Otto); Kellerman, T. Stephanus; Gelderblom, W.C.A.; Thiel, P.G.; Van der Lugt, Jaco J.(Published by the Government Printer, Pretoria., 1988)
Kellerman, T. Stephanus; Van der Westhuizen, G.C.A.; Coetzer, Jacobus A.W.; Roux, Cecilia; Marasas, Walter F.O. (Walter Friedrich Otto); Minne, J.A.; Basson, P.A.(Pretoria : The Government Printer, 1980)