“Using Multivariate Gray Model to Predict CO2 Emissions and People Using Safely Managed Sanitation Services”. Journal of Al-Rafidain University College For Sciences ( Print ISSN: 1681-6870 ,Online ISSN: 2790-2293 ) 54, no. 1 (January 13, 2024): 159–167. Accessed November 19, 2024. https://alhadhar.com/raf-journal/index.php/JAUCS/article/view/587.