TODD, SIMON W. «Gradients in vegetation cover, structure and species richness of Nama‐Karoo shrublands in relation to distance from livestock watering points» (en anglès). Journal of Applied Ecology, 43, 2, 31-03-2006, pàg. 293-304. DOI: 10.1111/j.1365-2664.2006.01154.x.