Safa, M., S. Fallah-Tafti, F. Talischi, and F. Ghassem-Boroujerdi. “Severity of Anxiety Disorders in Patients With Chronic Obstructive Pulmonary Disease”. Iranian Journal of Psychiatry, Vol. 10, no. 2, Feb. 2016, pp. 128-32, http://ijps.tums.ac.ir/index.php/ijps/article/view/394.