Gemo, Helder R.; Stevens, Joseph Benjamin; Chilonda, P.(South African Society for Agricultural Extension, Department of Agriculture, Ecomomics, Extensions and Rural Development, University of Pretoria, 2013)
Matiwane, M.B. (Mona Ben); Terblanche, S.E. (Stephanus Esaias), 1940-(South African Society for Agricultural Extension, Department of Agriculture, Ecomomics, Extensions and Rural Development, University of Pretoria, 2012)