Ridho Jatmiko Utama, and Bekman Siagian. “OPTIMAL STOCK PORTFOLIO USING SINGLE INDEX MODEL (Case Study: 50 Biggest Market Capitalization Listed on the Indonesia Stock Exchange for the Period January 2023 – December 2023)”. International Journal of Economic, Business, Accounting, Agriculture Management and Sharia Administration (IJEBAS) 5, no. 1 (February 25, 2025): 327–342. Accessed March 7, 2025. http://radjapublika.com/index.php/IJEBAS/article/view/2490.