Elpani, S. E., et al. “Utilization of Natural Coagulant Substance (Tamarind and Winged Bean Seed) on the Quality of Tofu Wastewater in Muntilan, Magelang”. Indonesian Journal of Chemistry and Environment, vol. 2, no. 1, Feb. 2020, pp. 25-32, doi:10.21831/ijce.v2i1.30294.