Smit, Michel, Marije Elferink-Gemser, Nikki Kolman, and Barbara Huijgen. “Monitoring Technical Tennis Performance under Increasing Physical Intensity by the PTTF-Test”. International Journal of Racket Sports Science 3, no. 2 (December 30, 2021): 49-58. Accessed February 16, 2025. https://journal.racketsportscience.org/index.php/ijrss/article/view/36.