Shabbir, Asma, Syed Badshah Hussain Zaidi, and Shazia Nisar. 2017. “FREQUENCY OF ECG ABNORMALITIES IN PATIENTS OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE ACCORDING TO DISEASE SEVERITY: ECG Abnormalities in Chronic Obstructive Pulmonary Disease”. Pakistan Armed Forces Medical Journal 67 (4):569-74. https://pafmj.org/PAFMJ/article/view/689.