Waheed, Aamir, et al. “STUDY OF DELIVERY PRACTICES OF OXYGEN BY HEALTHCARE PROFESSIONALS IN ACUTE EXACERBATION OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE”. Pakistan Armed Forces Medical Journal, vol. 71, no. 1, Feb. 2021, pp. 79-82, https://pafmj.org/PAFMJ/article/view/6359.