Ari Wijaya, Oscarius Yudhi. “Marketing Portfolio in Managing Uncertainty Risk During the Covid-19 Pandemic”. International Journal of Economics, Business and Accounting Research (IJEBAR) 5, no. 1 (April 5, 2021): 596–609. Accessed July 11, 2025. https://jurnal.stie-aas.ac.id/index.php/IJEBAR/article/view/1944.