tunik, tunik, Rahayu Niningasih, & Edi Yuswantoro. " The Effectiveness of Breath Relaxation with Balloon Blowing Technique towards Oxygen Saturation of COPD Patients." Jurnal Pendidikan Kesehatan (e-Journal) [Online], 9.2 (2020): 193 - 199. Web. 16 Apr. 2021