1. Vickerman, K., in Parasites in the Immunized Host: Mechanisms of Survival, Ciba Foundation Symp., 25 new series, 53–70 (Associated Scientific Publishers, Amsterdam, 1974).
2. Gray, A. R., J. gen. Microbiol., 41, 195–214 (1965).
3. Gray, A. R., Trans. R. Soc. Trop. med. Hyg., 69, 131–138 (1975).
4. Van Meirvenne, N., Janssens, P. G., and Magnus, E., Ann. Soc. belge. Med. trop., 55, 1–23 (1975).
5. Van Meirvenne, N., Janssens, P. G., Magnus, E., Lumsden, W. H. R., and Herbert, W. J., Ann. Soc. belge. Med. trop., 55, 25–30 (1975).