1) Weller, R. W.: Metaplasia of bronchial epithelium: A postmortem study. Amer. J. Clin. Pathol., 23: 768, 1953.
2) Auerbach, O., Gere, J. B., Forman, J. B., Petrick, T. G., Smolin, H. J., Muehsam, G. E., Kassouny, D. Y. & Stout, A. P.: Changes in the bronchial epithelium in relation to smoking and cancer of the lung. New Engl. J. Med., 256: 97, 1957.
3) Valentine, E. H.: Squamous metaplasia of bronchus; a study of metaplastic changes occurring in the epithelium of the major bronchi in cancerous and noncancerous cases. Cancer, 10: 272, 1957.
4) Nasiell, M.: The general appearance of the bronchial epithelium in bronchial carcinoma; a histopathological study with some cytological viewpoints. Acta Cytol., 7: 97, 1963.