(1) Bienenstock, J., and A.D. Befus. 1980. Mucosal immunology. Immunology 41: 249-270.
(2) Gordon, H.A. 1968. Is the germ-free animal normal? A review of its anomalies in young and old age, p.128-139. In M.E. Coates (ed.), The germ-free animal in research, Academic Press, London.
(3) Mackowiak, P.A. 1982. The normal microbial flora. New Engl. J. Med. 307: 83-93.
(4) Tomasi, T.B. 1983. Mechanisms of immune regulation at mucosal surface. Rev. Inf. Dis. 5: s784-s792.
(5) Ueda, K., S. Yamazaki, and S. Someya. 1973. Studies on tubercle bacillus infection in germfree mice. J. Reticuloendothel. Soc. 12: 545-563.