T. . Zehra, R. . Aamir, U. . Batool, W. . Sultan Baig, F. . Bacha, and N. . Riaz, “Evaluating the Factors Affecting the Occurrence of Symptomatic COVID-19 Illness after Vaccination”, Pakistan Journal of Medical & Health Sciences, vol. 16, no. 02, p. 139, Mar. 2022.