Poletti, V., and J. Egan. 2013. “Classification, Natural History and Staging of Idiopathic Pulmonary Fibrosis”. Sarcoidosis, Vasculitis and Diffuse Lung Diseases 30 (Suppl 1): 13-20. https://mattioli1885journals.com/index.php/sarcoidosis/article/view/3092.