Arbaningsih, S.R., Syarani, F., Ganie, R.A. and Lelo, A. 2019. The The Levels of Vitamin D, Metalloproteinase-9 and Tissue Inhibitor Metalloproteinase-1 in COPD Patients, Healthy Smokers and Non-Smokers of Indonesian Citizens. Open Access Macedonian Journal of Medical Sciences. 7, 13 (Aug. 2019), 2123–2126. DOI:https://doi.org/10.3889/oamjms.2019.612.