Long HT, Bảo NS, Dung TTK. Using oxalic acid as a standard for chemical oxygen demand determination with closed reflux–colorimetric method. hueuni-jns [Internet]. 2021Jul.5 [cited 2024Apr.25];130(1C):23-30. Available from: https://jos.hueuni.edu.vn/index.php/hujos-ns/article/view/6358