Pant, Pankaj, Shovit Thapa, Santa K Das, and Niraj Bam. 2019. “Serum Vitamin D Level in Chronic Obstructive Pulmonary Disease and Its Relation With Severity: A Single Centre Study”. Journal of Institute of Medicine Nepal 41 (2):56-58. https://nepjol.info/index.php/JIOM/article/view/26552.