Sartorius, Kurt; Kirsten, Johann F.(Independent Regulatory Board for Auditors (IRBA), SA Institute of Chartered Accountants (SAICA) & SA Association of Accountants (SAAA), 2004-06)
Zwane, E.M.; Duvel, G.H. (Gustav Heinrich)(South African Society for Agricultural Extension, Department of Agriculture, Ecomomics, Extensions and Rural Development, University of Pretoria, 2008)