Gallego Izquierdo, Tomás, et al. “Comparison of Cranio-Cervical Flexion Training Versus Cervical Proprioception Training in Patients With Chronic Neck Pain: A Randomized Controlled Clinical Trial”. Journal of Rehabilitation Medicine, vol. 48, no. 1, Nov. 2015, pp. 48-55, doi:10.2340/16501977-2034.