Sivri, Soner, and Oğuz Özbek. 2018. “Opinions of Tennis Umpires on in-Service Education umpires<p≫Tenis Hakemlerinin hizmetiçi eğitimlerine ilişkin görüşleri”. Journal of Human Sciences 15 (4):1791-1806. https://j-humansciences.com/ojs/index.php/IJHS/article/view/4644.