Potgieter, M.; De Jager, J.W.; Van Heerden, C.H.(Journal for New Generation Sciences, Vol 9, Issue 2: Central University of Technology, Free State, Bloemfontein, 2011)
Dzansi, D.Y.; Monnapula-Mapesela, M.(Journal for New Generation Sciences, Vol 10, Issue 3: Central University of Technology, Free State, Bloemfontein, 2012)
Delport, M.; Hay-Swemmer, D.; Wilkinson, A.(Journal for New Generation Sciences, Vol 12, Issue 1: Central University of Technology, Free State, Bloemfontein, 2014)