Kalfin, and Rizki Apriva Hidayana. “Optimization of Stock Portfolio in Indonesian Health Sector Using Markowitz Modern Portfolio Theory”. International Journal of Mathematics, Statistics, and Computing 3, no. 1 (February 3, 2025): 1–5. Accessed October 2, 2025. https://ejournal.corespub.com/index.php/ijmsc/article/view/182.