Trujillo Chávez, H. S., J. G. Tocto Lobato, Orlando David, and O. F. Sánchez Espinoza. “Concentration Routines in Intermediate Level Tennis Players”. Ciencia Digital, Vol. 4, no. 1, Jan. 2020, pp. 224-35, doi:10.33262/cienciadigital.v4i1.1096.