Kırkaya, I., C. Kaçoğlu, and B. Şenol. “Reliability and Concurrent Validity of Iphone®level Application for Measuring Lower Limb Active Flexion and Extension Range of Motions in Physical Education Students”. Physical Education of Students, vol. 25, no. 3, June 2021, pp. 164-71, doi:10.15561/20755279.2021.0304.