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 2024Nov.15];130(1C):23-30. Available from: http://222.255.146.83/index.php/hujos-ns/article/view/6358