J. Kühnis, B. Wachter, and C. Frommelt, “Involvement in Sports Clubs and Informal Sport Activities of Primary and Secondary School Children in Liechtenstein”, REI, vol. 9, no. 1/2, p. 10 f., May 2016, Accessed: Nov. 08, 2025. [Online]. Available: https://old.journals.um.si/index.php/education/article/view/370