Shaik Saffarudin, Muhammad Raees, Chee Hong Law, Koi Nyen Wong, and Soo Khoon Goh. “Unlocking the Inverted-U: Exploring the Threshold Impact of Population  Aging on Income Inequality Dynamics”. Technological and Economic Development of Economy (June 5, 2025): 1–20. Accessed June 11, 2025. https://journals.vilniustech.lt/index.php/TEDE/article/view/23762.