Saeed, A., A. Kalfah, and Z. Mohammed. “Comparing the Accuracy of Nasopharyngeal COVID-19 PCR Alone Versus Combined Nasopharyngeal and Oropharyngeal COVID-19 PCR Tests”. International Journal of Research in Medical Sciences, vol. 11, no. 11, Oct. 2023, pp. 3969-75, doi:10.18203/2320-6012.ijrms20233363.