1. Beigel, A. and Murphy, D. (1971). Am. J. Psychiat., 128, 688–94
2. Belluzzi, J. D. and Stein, L. (1977). Nature, 266, 556–8
3. Bloom, F., Segal, D., Ling, N. and Guillemin, R. (1976). Science, 194, 630–2 Byck, R. (1976). Lancet, II, 72–3
4. Cox, B., Ary, M. and Lomax, P. (1976). J. Pharmac. exp. Ther., 196, 637–41
5. Davis, G. C., Bunney, W. E. Jr, de Fraites, E. G., Kleinman, J. E., van Kammen, D. P., Post, R. M. and Wyatt, R. J. (1977). Science, 197, 74–7