1. Lurie, M. B., Resistance to Tuberculosis: Experimental Studies in Native and Acquired Defensive Mechanisms (Harvard University Press, Cambridge, 1964).
2. Raffel, S., in Immunological Diseases (edit. by Samter, M.), second ed. (Little, Brown and Co., Boston, 1971).
3. Uhr, J. W., Physiol. Rev., 46, 359 (1966).
4. Epstein, W. L., Progr. Allergy, 11, 36 (1967).
5. Spector, W. G., Int. Rev. exp. Pathol., 8, 1 (1969).