The antimicrobial, antimalarial and toxicity profiles of helihumulone, leaf essential oil and extracts of Helichrysum cymosum (L.) D. Don subsp. cymosum. - Van Vuuren,S.F.; Viljoen,A.M.; van Zyl,R.L.; van Heerden,F.R.; Başer,K.H.C. (S Afr J Bot, 2006)