Duvel, G.H. (Gustav Heinrich)(South African Society for Agricultural Extension, Department of Agriculture, Ecomomics, Extensions and Rural Development, University of Pretoria, 2008)
Terblanche, S.E. (Stephanus Esaias), 1940-(South African Society for Agricultural Extension, Department of Agricultural Ecomomics, Extension and Rural Development, University of Pretoria, 2007)
Collste, David; Aguiar, Ana Paula D.; Harmackova, Zuzana V.; Galafassi, Diego; Pereira, Laura M.; Selomane, Odirilwe; Van Der Leeuw, Sander(IOP Publishing, 2023-05-24)