AUTOMATIC SYSTEM FOR HAZARDOUS GAS, HUMAN DETECTION, TEMPERATURE MONITORING AND WATER LEVEL DETECTING IN COAL MINES USING GSM. International Journal of Mechanical Engineering Research and Technology , [S. l.], v. 14, n. 4, p. 37–45, 2022. Disponível em: https://ijmert.com/index.php/ijmert/article/view/110. Acesso em: 18 apr. 2026.