1. Hintze, J.L., 1997. Number cruncher statistical systems 2000, Kaysville, Utah
2. Hoffman, J.E., 1990. Die invloed van grondbewerkingspraktyke op die waterbalans van ’n Avalongrond onder koring te Bethlehem. M.Sc. Agric. verhandeling, Universiteit van die Vrystaat, Bloemfontein
3. Pekrun, C., Kaul, H.P. & Claupein, W., 2003. Soil tillage for sustainable nutrient management.In: A.E. Titi (ed.). Soil tillage in agroecosystems. CRC Press, London
4. Soil Survey Staff, 1987. Keys to soil taxonomy. SMSS technical monograph no. 6, Ithaca, New York