Joubert, C.S.; Schoeman, N.J. (Nicolaas Johannes); Blignaut, James Nelson(Faculty of Economic and Management Sciences, University of Pretoria, 1999-03)
Grote, M.; Schoeman, N.J. (Nicolaas Johannes); Truu, M.L.; Van Heerden, J.H. (Jan Horn), 1957-; Van Tonder, Jurie J.(Faculty of Economic and Management Sciences, University of Pretoria, 2000-03)