Junquera-Tortosa , M, et al. “INTRA-EXAMINER RELIABILITY AND VALIDITY CRITERIA OF A SMARTPHONE APPLICATION TO MEASURE THE TEST FLEXION-ROTATION IN CERVICAL SPINE IN ASYMPTOMATIC SUBJECTS”. Cuestiones De Fisioterapia, vol. 48, no. 1, Feb. 2019, pp. 04-10, http://cuestionesdefisioterapia.es/index.php/cf/article/view/121.