Siew-Theng, F., W.-. Loy Chu, and P. Siew-Moi. “Tolerance of Four Malaysian Chlorophytes to Nitrate and Ammonium Pollution”. Malaysian Journal of Science, vol. 20, no. 1, Apr. 2001, pp. 15-20, https://ajba.um.edu.my/index.php/MJS/article/view/8770.