Anggraeni, D., K. . Sugiyanto, M. I. . Zam Zam, and H. . Patria. “PORTFOLIO OPTIMIZATION FOR SHIPPING &Amp; DELIVERY SERVICES WITH R: BEFORE AND AFTER PANDEMIC COVID-19”. Fair Value: Jurnal Ilmiah Akuntansi Dan Keuangan, vol. 4, no. 6, Jan. 2022, pp. 550-63, doi:10.32670/fairvalue.v4i6.847.