Koopmann, T., I. Faber, D. Büsch, and J. Schorer. “The Oldenburg Observation Sheet for Table Tennis Technique (O3T) As a Tool for Talent Identification and Development: A Reliability, Validity and Feasibility Study”. International Journal of Racket Sports Science, Vol. 4, no. 2, Dec. 2022, pp. 20-31, https://journal.racketsportscience.org/index.php/ijrss/article/view/75.