Siew-Theng, Foo, Wan- Loy Chu, and Phang, Siew-Moi. 2001. “Tolerance of Four Malaysian Chlorophytes to Nitrate and Ammonium Pollution”. Malaysian Journal of Science 20 (1):15-20. https://ejournal.um.edu.my/index.php/MJS/article/view/8770.