Rammayan, T., and P. Boonyarit. “Prevalence of Musculoskeletal Symptoms at Upper Body Parts Due to Smartphone Using Among Lower Secondary School Students”. Srinagarind Medical Journal, vol. 31, no. 6, Jan. 2017, pp. 392-9, https://li01.tci-thaijo.org/index.php/SRIMEDJ/article/view/75280.