Hama Amin, Dlpak Ahmed. “Air Pollution in Kalar City by Carbon Monoxide and Carbon Dioxide Gases”. Halabja University Journal 5, no. 1 (March 30, 2020): 478–491. Accessed April 29, 2024. https://huj.uoh.edu.iq/index.php/HUJ/article/view/huj-10283.