Yohan, Yohan, Fifit Astuti, and Adimas Wicaksana. “Colorimeter Portable to Determine Ammonium Using to Manure Tetector”. Piston: Journal of Technical Engineering 4, no. 2 (January 15, 2021): 48–55. Accessed November 23, 2024. https://openjournal.unpam.ac.id/index.php/Piston/article/view/9617.