Van Deventer, P.J.; Snyman, M.M.M. (Maria Magdalena Margaretha); Snyman, Retha(Department of Knowledge and Information Management, University of Johannesburg, 2004-03)
Rademeyer, P.; Snyman, M.M.M. (Maria Magdalena Margaretha); Snyman, Retha(Department of Knowledge and Information Management, University of Johannesburg, 2004-09)