Mrozkowiak, M., Szark-Eckard, M., Żukowska, H., & Hadlich, R. (2016). The impact of physical activity in the ‘Keep your body straight” program on the selected features of body posturę in sagittal plane in children aged 7-9 years. Medical and Biological Sciences, 30(3), 67–72. https://doi.org/10.12775/MBS.2016.025