E. K. Z. , M. M. A. Eman Yassin Salem , Tran., “Impact of Incentive Spirometry on Diaphragmatic Excursion in upper abdominal surgeries”, int.jour.sci.res.mana, vol. 5, no. 8, pp. 6899–6914, Aug. 2017, doi: 10.18535/ijsrm/v5i8.43.