Erdvik, Irina Burchard, Tommy Haugen, Andreas Ivarsson, og Reidar Säfvenbom. «Development of Basic Psychological Need Satisfaction in Physical Education: Effects of a Two-Year PE Programme». Journal for Research in Arts and Sports Education 3, no. 2 (november 20, 2019). åpnet april 26, 2024. https://jased.net/index.php/jased/article/view/1375.