E. Hassan, N. A. Mohamad Mustafa, N. A. Salahuddin, and S. A. Md Arepen, “Viral Load, Detection Rate and Sensitivity of Nasopharyngeal and Oropharyngeal Swab Sampling for Diagnosis of COVID-19 ”, UIJ, vol. 33, no. 3, pp. 35–50, Jun. 2021.