R. Martínez-Gallego, J. F. Guzmán, N. James, J. Ramón-Llin, M. Crespo, and G. Vuckovic, “The relationship between the incidence of winners/errors and the time spent in different areas of the court in elite tennis”, J. Hum. Sport Exerc., vol. 8, no. 3proc, pp. S601-S607, Dec. 2013.