Schmidli, B. C., S. Endes, S. D. Stoffel Kerr, and C. R. Nigg. “Validating Device-Based Physical Activity Indicators With Observation Physical Activity Indicators in Swiss Pre-School Children”. Current Issues in Sport Science (CISS), vol. 8, no. 2, Feb. 2023, p. 070, doi:10.36950/2023.2ciss070.