Herry Cahyana, Antonius, et al. “Prenylation of Xanthone Extract from Mangosteen (Garcinia Mangostana L.) Rind by Using Superbase Catalyst of G-Alumina NaOH Na and Antioxidant Activity Test”. Asian Journal of Chemistry, vol. 27, no. 6, Mar. 2015, pp. 2228-30, doi:10.14233/ajchem.2015.18588.