found: Katzenstein, L. Secrets of St. John's wort, c1998:p. 17.
found: St. John's wort : the mood enhancer, c1997:index.
found: USDA Plants Database, June 18, 2008:name search (Hypericum perforatum, Common St. Johnswort)
found: Interactive Flora of NW Europe website, June 18, 2008:species search (Hypericum perforatum, Perforate St. John"s-wort)
found: Wikipedia online, June 25, 2008(St. John's wort; used alone refers to the species Hypericum perforatum; also known as: Tipton's Weed or Klamath weed; Hypericum perforatum is also sometimes called: Common St. John's wort to differentiate it from other species of Hypericum)