Nyembwe, K.; De Beer, D.; Van der Walt, K.; Bhero, S.(Interim : Interdisciplinary Journal, Vol 10 , Issue 1: Central University of Technology Free State Bloemfontein, 2011)
Truscott, M.; Janse van Vuuren, M.; Booysen, G.; De Beer, D.(Interim : Interdisciplinary Journal, Vol 7, Issue 1: Central University of Technology Free State Bloemfontein, 2008)
Gibson, I.; Liu, Y.; Savalani, M.M.; Anand, L.K.;(Journal for New Generation Sciences, Vol 7, Issue 3: Central University of Technology, Free State, Bloemfontein, 2009)
Dimitrov, D.; De Beer, N.; Centner, T.(Journal for New Generation Sciences, Vol 4, Issue 1: Central University of Technology, Free State, Bloemfontein, 2006)