Bonella, F., A. Volpe, and P. Caramaschi, et al. 2011. “Surfactant Protein D and KL-6 Serum Levels in Systemic Sclerosis: Correlation With Lung and Systemic Involvement”. Sarcoidosis, Vasculitis and Diffuse Lung Diseases 28 (1): 27-33. https://mattioli1885journals.com/index.php/sarcoidosis/article/view/2618.