Schmidt, A., Wächtler, B., Temp, U., Krekling, T., Seguin, A., & Gershenzon, J. (2010). A bifunctional geranyl and geranylgeranyl diphosphate synthase is involved in terpene oleoresin formation in Picea abies. Plant Physiology, 152, 639-655. doi:10.1104/pp.109.144691.