Lubis, E. F. “CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) MANAGEMENT IN OLD MALE WITH HISTORY AS ACTIVE SMOKERS”. Jurnal Kesehatan Dan Agromedicine, vol. 1, no. 2, Nov. 2014, pp. 92-99, https://juke.kedokteran.unila.ac.id/index.php/agro/article/view/1301.