Ratanamaitrekeart, R., and N. Piphatvanitcha. “Factors Related to Spiritual Needs Among Older Adult Patients Undergoing Elective Surgery”. Journal of Research in Nursing-Midwifery and Health Sciences, vol. 37, no. 2, June 2017, pp. 14-26, https://he02.tci-thaijo.org/index.php/nur-psu/article/view/91371.