Arney, B. E., R. Glover, A. Fusco, C. Cortis, J. J. de Koning, T. van Erp, S. Jaime, R. P. Mikat, J. P. Porcari, and C. Foster. “Comparison of Rating of Perceived Exertion Scales During Incremental and Interval Exercise”. Kinesiology, vol. 51, no. 2, July 2019, pp. 150-7, https://hrcak.srce.hr/ojs/index.php/kinesiology/article/view/6882.