Tamanampo, Jan W. F. S., et al. “Cumulatif Valuation of Physic-Chemical Water Quality from Tondano Lake, North Sulawesi”. Jurnal Ilmiah PLATAX, vol. 5, no. 2, Apr. 2017, pp. 135-44, doi:10.35800/jip.5.2.2017.15533.