Lis, Andrzej, and Mateusz Tomanek. “Mapping the Intellectual and Conceptual Structure of Physical Education Research: Direct Citation Analysis”. Physical education of students 25, no. 2 (April 30, 2021): 67-84. Accessed December 5, 2021. https://sportedu.org.ua/index.php/PES/article/view/1307.