White ES, Xia M, Murray S, Dyal R, Flaherty CM, Flaherty KR, Moore BB, Cheng L, Doyle TJ, Villalba J, Dellaripa PF, Rosas IO, Kurtis JD, Martinez FJ. Plasma Surfactant Protein-D, Matrix Metalloproteinase-7, and Osteopontin Index Distinguishes Idiopathic Pulmonary Fibrosis from Other Idiopathic Interstitial Pneumonias. Am J Respir Crit Care Med. 2016 11 15; 194(10):1242-1251.