CHAND, A.; SEN, N. K.; SINGH, S. Determination of free acidity in aluminium sulphate and alum using hexamine and potassium fluoride as complexing agent. Defence Science Journal, [S. l.], v. 12, n. 1, p. 79–88, 2014. DOI: 10.14429/dsj.12.6837. Disponível em: https://publications.drdo.gov.in/ojs/index.php/dsj/article/view/6837. Acesso em: 3 jul. 2025.