1. D. R. Curtis and G. A. R. Johnston, Ergebn. Physiol.69, 97 (1974).
2. K. Krnjević, Physiol. Rev.54, 418, (1974).
3. F. V. DeFeudis, A. Rev. Pharmac.15, 105 (1975).
4. F. V. DeFeudis, Int. Rev. Neurobiol. in press (1977).
5. G. A. R. Johnston, in: Chemical Transmission in the Central Nervous System, p. 38. Ed. C. H. Hockman and D. Bieger. Univ. Park Press, Baltimore 1976.