Pandiangan, Naomi, Sukono Sukono, and Endang Soeryana Hasbullah. “Quadratic Investment Portfolio Based on Value-at-Risk With Risk-Free Assets: For Stocks of the Mining and Energy Sector”. International Journal of Energy Economics and Policy 11, no. 4 (June 8, 2021): 175–184. Accessed January 10, 2025. https://mail.econjournals.org.tr/index.php/ijeep/article/view/11165.