Fatahi, Ali, et al. “Maintenance of Physical Fitness Levels in Junior Volleyball Players During COVID-19 With Protective Measures Against the Pandemic Condition: Maintenance of Physical Fitness in Volleyball Players During COVID-19”. Journal of Clinical Physiotherapy Research, vol. 6, no. 1, Jan. 2021, p. e27, doi:10.22037/jcpr.v6i1.33304.