Kruit, A., et al. “CA 15-3 As an Alternative Marker for KL-6 in Fibrotic Lung Diseases”. Sarcoidosis, Vasculitis and Diffuse Lung Diseases, vol. 27, no. 2, Dec. 2010, pp. 138-46, https://mattioli1885journals.com/index.php/sarcoidosis/article/view/2579.