1. https://www.aidic.it/cet/17/59/101.pdf
2. https://www.uni-obuda.hu/journal/Bingol_Tasdelen_Keskin_Kocaturk_49.pdf
3. https://www.cpsc.gov/s3fs-public/WPI2015SmokeAlarmReport.pdf
4. https://www.researchgate.net/profile/R_Naayagi/publication/262163562_Design_and_Implementation_of_an_Economic_Gas_Leakage_Detector/links/56289a5e08ae518e347c5b20/Design-and-Implementation-of-an-Economic-Gas-Leakage-Detector.pdf
5. https://www.thomasnet.com/articles/instruments-controls/How-Gas-Detectors-Work/