Soil Science Society of Southern Africa : Grondkundevereniging Van Suidelike Afrika : Handelinge 8ste Nasionale Kongres, Pietermaritzburg 1978 : Vordering in Grondkunde in Suidelike Afrika, 1953-1978 Proceedings 8th National Congress, Pietermaritzburg 1978 : Advances in Soil Science in Southern Africa 1953-1978