Elly Susanti, Nelly Ervina, Ernest Grace, Liper Siregar. Comparison Analysis Of Optimal Portfolio Formation Results Using Single Index Model With Markowitz Model During The Covid 19 Pandemic In LQ 45 Index Company. IJERSC [Internet]. 2021Nov.5 [cited 2024Nov.7];2(5):1146-5. Available from: https://ijersc.org/index.php/go/article/view/177