Long, Hoàng Thái, Nguyễn Sỹ Bảo, and Tạ Thị Kim Dung. “Using Oxalic Acid As a Standard for Chemical Oxygen Demand Determination With Closed reflux–colorimetric Method”. Hue University Journal of Science: Natural Science 130, no. 1C (July 5, 2021): 23-30. Accessed November 26, 2024. https://jos.hueuni.edu.vn/index.php/hujos-ns/article/view/6358.