Use of a panel of tumor markers (carcinoembryonic antigen, cancer antigen 125, carbohydrate antigen 15–3, and cytokeratin 19 fragments) in pleural fluid for the differential diagnosis of benign and malignant effusions - Porcel,J.M.; Vives,M.; Esquerda,A.; Salud,A.; Perez,B.; Rodriguez-Panadero,F. (Chest, 2004)