1. Wheelock, E. F., and Toy, S. T., Adv. Immun., 16, 123–184 (1973).
2. Notkins, A. L., J. exp. Med., 134, 41s–51s (1971).
3. Choppin, P. W., in Textbook of Immunopathology, (edit. by Miescher, P. A., and Muller-Eberhard, H. J.), 1, 337–349 (Grune and Statton, New York, 1968).
4. Eklund, C. M., Kennedy, R. C., and Hadlow, W. J., J. infect. Dis., 117, 15–22 (1967).
5. Kimberlin, R. H., Scrapie in the mouse: a model slow disease, (Merrow Monograph, 1974).