NAYAK, J.; BERA, J. A simple method for production of humidity indicating silica gel from rice husk ash. Journal of Metals, Materials and Minerals, Bangkok, Thailand, v. 19, n. 2, 2017. Disponível em: http://jmmm.material.chula.ac.th/index.php/jmmm/article/view/230. Acesso em: 21 jan. 2022.