LUDENA-HUAMAN, Michael A.  and  RAMOS-LNQUILTUPA, Deborah A.. Determination of the content of ursolic and oleanolic acid in the cuticular wax of fruits of different species of Rosaceae. Rev.Colomb.Quim. [online]. 2019, vol.48, n.2, pp.15-20.  Epub June 26, 2019. ISSN 0120-2804.