Moller, H.; Govender, G.; Stumpf, W.E(Journal for New Generation Sciences, Vol 8, Issue 2: Central University of Technology, Free State, Bloemfontein, 2010)
Kotze, B.; Jordaan, G.D.; Vermaak, H.(Journal for New Generation Sciences, Vol 8, Issue 3: Central University of Technology, Free State, Bloemfontein, 2010)
Pretorius, J.P.H.; Von Maltitz, M.J.(Journal for New Generation Sciences, Vol 8, Issue 3: Central University of Technology, Free State, Bloemfontein, 2010)
Moeti, L.; De Wet, L.; Beelders, T.(Journal for New Generation Sciences, Vol 8, Issue 3: Central University of Technology, Free State, Bloemfontein, 2010)