Dippenaar-Schoeman, Anna S. (Anna Sophia), 1948-; Van den Berg, Almie; Lyle, Robin; Haddad, Charles R.; Foord, Stefan Hendrik; Lotz, Leon N.(AOSIS Open Journals, 2013-04-19)
Koch, B.H.; Terblanche, S.E. (Stephanus Esaias), 1940-(South African Society for Agricultural Extension, Department of Agriculture, Ecomomics, Extensions and Rural Development, University of Pretoria, 2013)