1. Expert Choice 11.5;Anonymous,2004
2. Blignaut, J., Milton, S., Cupido, C., 2005. The Economic Value of Controlling Invasive Alien Plant Species in the Karoo. Unpublished report, October 2005. Working for Water, Cape Town.
3. National Water Resources Strategy;DWAF,2004
4. Arc/Info Command Line; ArcView Desktop GIS Software Versions 3.x.; ArcGIS 9.3.1;Environmental Systems Research Institute (ESRI),1990-2009
5. Expert Consultation on Weed Risk Assessment;FAO,2003