1. 2004. Gerbera Pest Management Newsletter, issue 1, http://entomology.ucdavis.edu/faculty/parrella/gpma/file/newsletter1.pdf
2. 1999 onwards. Sales of cut flowers and foliage through the Dutch Auctions. September 2002, http://www.pathfast.com/docs/Manual.htm
3. 2001 onwards. Angiosperm Phylogeny Website. Version 6, May 2005, http://www.mobot.org/MOBOT/research/APweb/