Jaafar F, M., A. A. Hadi, I. N.H, and K. Awang. “Indole Alkaloids of Leuconotis Eugenifolius”. Malaysian Journal of Science, vol. 24, no. 1, Jan. 2005, pp. 129-31, https://juku.um.edu.my/index.php/MJS/article/view/8945.