1. Foulds, L. Neoplastic Development Vols 1 and 2 (Academic, London, 1969 and 1975).
2. Scherer, H. J. Amer. J. Cancer 40, 159–198 (1940).
3. Russel, D. S. & Rubenstein, L. J. in Pathology of Tumors of the Nervous System 4th edn 226–228 (Williams and Wilkins, Baltimore, 1977).
4. Nowell, P. Science 194, 23–28 (1976).
5. James, C. D. et al. Cancer Res. 48, 5546–5551 (1988).