N. Ibekwe, Nneka, et al. “Phytochemical Constituents of the Leaves of Landolphia Owariensis: doi.org 10.26538 Tjnpr V3i8.2”. Tropical Journal of Natural Product Research (TJNPR), vol. 3, no. 8, Aug. 2019, pp. 261-4, https://www.tjnpr.org/index.php/home/article/view/994.