Annisa, I. N., D. Yuniasih, and N. W. Sukirto. “Systematic Review and Meta-Analysis: Effect of Zinc Levels in COVID-19 Patients on Their Clinical Severity”. Ahmad Dahlan Medical Journal, vol. 4, no. 2, Nov. 2023, pp. 179-90, http://journal2.uad.ac.id/index.php/admj/article/view/9015.