Woitas-Ślubowska, D., E. Hurnik, A. Skarpańska-Stejnborn, and R. Gotowski. “Does past Participation in Competitive Sports Affect the Relationships Between Socioeconomic Factors and Self-Rated Health: Study Randomly Selected Polish Male and Female Former Athletes and Non-Athletes”. Journal of Education, Health and Sport, vol. 8, no. 1, Jan. 2018, pp. 148-62, https://apcz.umk.pl/JEHS/article/view/5252.