Usman, U. “Comparison Analysis Of Optimal Portfolio With The Capital Asset Pricing Model (CAPM) Before And During The Covid-19 Pandemic : Study on Liquid-45 Index Stock Period 2018-2021”. AJIRSS: Asian Journal of Innovative Research in Social Science, vol. 1, no. 3, Aug. 2022, pp. 89-97, doi:10.53866/ajirss.v1i3.157.