Keawsengsai, A., K. . Suchamvang, and P. Nanasilp. “Effect of Iyengar Yoga Exercise on Severity of Knee Osteoarthritis Among the Older Persons”. Nursing Journal CMU, vol. 47, no. 1, Mar. 2020, pp. 175-84, https://he02.tci-thaijo.org/index.php/cmunursing/article/view/240743.