Ye J, Findeis-Hosey JJ, Yang Q, McMahon LA, Yao JL, Li F, Xu H. Combination of napsin A and TTF-1 immunohistochemistry helps in differentiating primary lung adenocarcinoma from metastatic carcinoma in the lung. Appl Immunohistochem Mol Morphol. 2011 Jul; 19(4):313-7.