Meliala FU, Sukarno S. Optimal Investment Portfolio Analysis Using The Markowitz Model For Stock In Each Sector In The Indonesia Stock Market During Covid 19 (2020-2021). jrssem [Internet]. 2023Mar.27 [cited 2024Nov.24];2(8):1884 -. Available from: https://jrssem.publikasiindonesia.id/index.php/jrssem/article/view/399