Groffik, Dorota, Karel Frömel, Marta Witek-Chabińska, Rafał Szyja, Radim Žatka, and Bartosz Urbański. 2019. “Daily and School Physical Activity of 16 Year-Old Girls and Boys”. Health Promotion & Physical Activity 4 (3):12-19. https://doi.org/10.5604/01.3001.0012.8669.