LONG, H. T.; BẢO, N. S.; DUNG, T. T. K. Using oxalic acid as a standard for chemical oxygen demand determination with closed reflux–colorimetric method. Hue University Journal of Science: Natural Science, [S. l.], v. 130, n. 1C, p. 23-30, 2021. DOI: 10.26459/hueunijns.v130i1C.6358. Disponível em: https://jos.hueuni.edu.vn/index.php/hujos-ns/article/view/6358. Acesso em: 24 apr. 2024.