Fadhil, Atheer A., et al. “The Use of Volumetric Chest Computed Tomography in Determination of Chronic Obstructive Pulmonary Disease Phenotypes”. Journal of the Faculty of Medicine Baghdad, vol. 56, no. 1, Apr. 2014, pp. 20-24, https://doi.org/10.32007/jfacmedbagdad.561419.