1. Janeway, C. A., Travers, P., Walport, M. & Shlomchik, M. Immunobiology 5th edn (Garland, New York, 2004)
2. Goldsby, R. A., Kindt, T. J., Osborne, B. & Kuby, J. Immunology 4th edn (Freeman, New York, 2002).
3. Thucydides, T. B. C. R. The Peloponnesian War (Dutton, New York, 1910). (Translated by J. M. Dent.)
4. Pasteur, L. in Milestones in Microbiology (Ed. Brock, T.) 121–125 (American Society for Microbiology, Washington DC, 1998).
5. Salmon, D. & Smith, T. On a new method of producing immunity from contagious diseases. Am. Vet. Rev. 10, 63–69 (1886).