Lekhooa, M., A. Walubo, J. J. Du Plessis, and M. G. Matsabisa. “Evaluation of Traditional Medicines III: The Mechanism of Immune Modulation by PHELA”. African Journal of Traditional, Complementary and Alternative Medicines, vol. 9, no. 3S, Jan. 2012, pp. 47-63, https://journals.athmsi.org/index.php/ajtcam/article/view/1493.