Ulan Dari, G., Dedy Hamdani and Iwan Setiawan 2023. Design and Build a Hazardous Gas Monitoring Device (CO, CO2, CH4) Upon Cigarette Smoke in an Enclosed Space Based on Arduino Uno and GSM SIM 900 A . Journal of Research and Technology. 8, 2 (Feb. 2023), 289–302. DOI:https://doi.org/10.55732/jrt.v8i2.696.