Kurniawan, Zahir, Nur Ariyani Agustina, and Bayu Pratomo. “Analysis of Sungai Ular Water Quality Viewed from The Impact of Palm Oil Industry Activities And PDAM”. Jurnal Online Pertanian Tropik 7, no. 3 (May 5, 2021): 326–334. Accessed August 4, 2025. https://idjpcr.usu.ac.id/jpt/article/view/5481.