1. Lucid, Centre for Pest Information Technology and Transfer, Uniersity of Queensland, available at http://www.lucidcentral.com, accessed November 2006
2. Uconn plant database of trees, shrubs and vines, University of Connecticut Home and Garden Center, available at http://www.hort.uconn.edu/plants/index.html, accessed November 2006
3. CalFlora, UC Berkeley Digital Library Project, available at http://www.calflora.org/index0.html, accessed November 2006
4. Reliable classification of chrysanthemum leaves through Curvature Scale Space