I, Noorbatcha, Hassan S, Hamid A. Hadi, and Khalijah Awang. 2002. “Ab Initia Geometry-Optimization and NMR Studies of Chemical Constituents of Piper Sarmentosum”. Malaysian Journal of Science 21 (1&2):143-47. https://samudera.um.edu.my/index.php/MJS/article/view/8600.