Kowalska, Jolanta E., et al. “The Reasons for Undertaking Physical Activity by Seniors from małopolska Voivodship (based on Polsenior Study)”. Exlibris Social Gerontology Journal, vol. 11, no. 1, Sept. 2016, pp. 131-46, https://ojs.wsb.edu.pl/index.php/bgs/article/view/713.