Novie NEM, Desintra DED. Environmental Factors As The Risk Factors Of The Degrees Severity Chronic Obstructive Pulmonary Diseases on Elderly. jkkes [Internet]. 2021Feb.13 [cited 2025Jan.31];14(2):109-15. Available from: http://ejournal.stikesjayc.id/index.php/litkartika/article/view/97