Composition #5: Perry, Nigel B., Burgess, Elaine J., Rodriguez Guitian, Manuel A., Romero Franco, Rosa., Lopez Mosquera, Elvira., Smallfield, Bruce M., Joyce, Nigel I., Littlejohn, Roger P. Sesquiterpene Lactones in Arnica montana: Helenalin and Dihydrohelenalin Chemotypes in Spain . planta medica, 2009, vol. 75, no. 6, p. 660–666. DOI: 10.1055/s-0029-1185362.
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