AUTOMATIC SYSTEM FOR HAZARDOUS GAS, HUMAN DETECTION, TEMPERATURE MONITORING AND WATER LEVEL DETECTING IN COAL MINES USING GSM. International Journal of Engineering and Science Research, [S. l.], v. 13, n. 3, p. 1–9, 2023. Disponível em: https://www.ijesr.org/index.php/ijesr/article/view/984. Acesso em: 7 aug. 2025.