Saputro, Ardian Dwi, and Siti Aisyah. “The Analysis of Income Gap in Lower Middle-Income Countries”. Journal of Economics Research and Social Sciences 7, no. 1 (February 23, 2023): 12–20. Accessed May 17, 2025. https://journal.umy.ac.id/index.php/jerss/article/view/16606.