Wyanov, Uska, and Imo Gandakusuma. “Optimal Portfolio Formation Analysis Vs. Single Index Model: 2018–2019 Before Crisis and 2020–21 During Crisis”. Jurnal Manajemen Bisnis 10, no. 2 (September 29, 2023): 588–596. Accessed May 16, 2025. https://jurnal.fe.umi.ac.id/index.php/JMB/article/view/576.