Mohammad, W. S. ., and W. M. . El-Sais. “Prevalence of Non-Specific Self-Reported Back Pain Among Adolescents at Hail Territory-KSA”. Journal of Asian Scientific Research, vol. 3, no. 10, Oct. 2013, pp. 1036-45, https://archive.aessweb.com/index.php/5003/article/view/3554.