V. Sethu, A. Selvarajoo, C. W. Lee, P. Ganesan, G. S. Lim, and X. Y. Mok, “Opuntia Cactus as a Novel Bio-coagulant for the Treatment of Palm Oil Mill Effluent (POME)”, Prog. Energy Environ., vol. 9, pp. 11–26, Jul. 2019.