Richard C. S, Wong, Chan, Chun Foong, and Wong, Hong Wee. “Distribution of Heavy Metals Found in Three Major Rivers of North-Eastern Pulau Langkawi”. Malaysian Journal of Science 24 (April 28, 2005): 9–14. Accessed May 11, 2024. https://ejournal.um.edu.my/index.php/MJS/article/view/8813.