Kokt, D.; Lategan, L.O.K.; Orkin, F.M.(Journal for New Generation Sciences, Vol 10, Issue 3: Central University of Technology, Free State, Bloemfontein, 2012)
De Beer, N.; Christelis, L.; Van der Merwe, A.F.(Journal for New Generation Sciences, Vol 10, Issue 3: Central University of Technology, Free State, Bloemfontein, 2012)
Mahlomaholo, Sechaba M.G.; Molebatsi, Milton M.; Francis, Dennis(Journal for New Generation Sciences, Vol 10, Issue 2: Central University of Technology, Free State, Bloemfontein, 2012)