Leardphadungchai, C., and J. Poonsawat. “Effect of the Yoga on Flexibility of the Back Part of Body of Female Students”. Kasetsart Journal of Social Sciences, vol. 28, no. 1, Apr. 2007, pp. 36-42, https://so04.tci-thaijo.org/index.php/kjss/article/view/246421.