Hafeez, Shakir, et al. “Relationship Among Perceived Stress, Academic Performance and Use of Energy Drinks: A Study on Universities’ and Medical Students of Khyber Pakhtunkhwa Province of Pakistan”. International Review of Management and Marketing, vol. 6, no. 3, July 2016, pp. 494-9, https://econjournals.org.tr/index.php/irmm/article/view/2421.