Smoła, E., K. Wódka, M. A. Bibro, and A. Jankowicz-Szymańska. “Flexibility of the Hamstring Muscles and the Position of the Trunk in Boys Training Football”. Health Promotion & Physical Activity, vol. 15, no. 2, June 2021, pp. 9-14, doi:10.5604/01.3001.0014.9505.