Bilal, Ahmad, and Minahil Aamir. “THREAT OF COVID-19 AND PERCEIVED STRESS: THE MEDIATING ROLE OF CHALLENGE, UNCONTROLLABILITY AND STRESSFULNESS: Threat of COVID-19 And Perceived Stress”. Pakistan Armed Forces Medical Journal, vol. 71, no. 5, Oct. 2021, pp. 1571-76, doi:10.51253/pafmj.v71i5.4332.