Sylvia Noviani Saing, G. Satria, Bermansyah, and Irfannuddin. “Effectiveness of Preoperative Incentive Spirometry in Patients Following Elective Thoracotomy for Prevention of Postoperative Pulmonary Complication”. Sriwijaya Journal of Surgery, Vol. 4, no. 2, June 2021, pp. 422-3, doi:10.37275/sjs.v4i2.66.