Omara, Tarek Mahmoud. “Ridge and Liu-Type Estimators for Tobit SUR Model: Application to Air Pollution Data”. Journal of Multidisciplinary Applied Natural Science 6, no. 2 (March 14, 2026): 1011–1028. Accessed June 30, 2026. https://journal.pandawainstitute.com/index.php/jmans/article/view/372.