Van Heerden, Neels, 1957-; Van Heerden, Cornelius Hendrik, 1957-; Schreuder, A.N.; Gouverneur, M.(Faculty of Economic and Management Sciences, University of Pretoria, 2000-03)
North, Ernest J.; Millard, Sollie M.(Innovatio Publishers (Germany), Media Tenor (South Africa) and the Institute for Media Analysis in South Africa (Imasa), 2003)