Pandiangan, N., Sukono, S., & Hasbullah, E. S. (2021). 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(4), 175–184. Retrieved from https://www.econjournals.com/index.php/ijeep/article/view/11165