1. Flaster T, Lassiter J (2004) HerbalGram 63:32–37
2. Slifman NR, Obermeyer WR, Aloi BK, Musser S, Correll WA Jr, Cichowicz SM, Betz JM, Love LA (1998) N Engl J Med 339(12):806–811
3. Frank MS, Perkins KD (ed) (2007) Preparation of plant specimens for deposit as herbarium vouchers. http://www.flmnh.ufl.edu/herbarium/voucher.htm. Cited 14 Mar 2007
4. Horton D (2003) Herbaria and specimens: What are they? http://www.cgrer.uiowa.edu/herbarium/HerbariaAndSpecimens.htm. Cited 14 Mar 2007
5. Bridson D, Forman L (eds) (1998) The herbarium handbook, 3rd edn. Royal Botanic Gardens, Kew