1. Sala, O.E. & Aguiar, M.R. (1996) Origin, maintenance, and ecosystem effect of vegetation patches in arid lands, in Rangelands in a Sustainable Biosphere (West, N., ed.) (Proceedings of the Fifth International Rangeland Congress Vol. 2), pp. 29–32, Society for Range Management, Denver
2. The Butana grass patterns;Worral;J. Soil Sci.,1959
3. Patchiness in vegetation in the northern Sudan;Worral;J. Ecol.,1960
4. Vegetation stripes in Somaliland;Boaler;J. Ecol.,1962
5. Observations of vegetation arcs in the northern region, Somali Republic;Boaler;J. Ecol.,1964