• Comprehensive investigation of St.John's Worth (Hypernicum perforatum) : polyphenolic compounds, essential oils and metalsHelmja, Kati; Vaher, Merike; Orav, Anne; Viitak, Anu; Püssa, Tõnu; Kaljurand, Mihkel14th International Symposium on Separation Science : Primosten, Croatia, 30 Sept. - 3 Oct. 20082008 / p. 59