1. Young, J. Z., in Evolution, edit. by de Beer G. R.,179 (Clarendon Press, Oxford, 1938)
2. Konorski, J., Conditioned Reflexes and Neurone Organization (Cambridge University Press, Cambridge, 1948).
3. Hebb, D. O., The Organization of Behavior: A Neuropsychological Theory (Wiley, New York, 1949).
4. Gerard, R. W., Amer. J. Psychiat., 106, 161 (1949).
5. Eccles, J. C., The Neurophysiological Basis of Mind: The Principles of Neurophysiology (Clarendon Press, Oxford, 1953).