Ivanov, Georgi. 2021. “STRUCTURAL FEATURES AND INTERACTIONS BETWEEN THE INDICATORS CHARACTERISING THE PHYSICAL AND THE TECHNICAL QUALITIES OF THE 12-14 YEARS OLD FOOTBALL PLAYERS PLAYING ON DIFFERENT GAME POSITIONS”. KNOWLEDGE - International Journal 49 (6):1317-22. https://ojs.ikm.mk/index.php/kij/article/view/4506.