1. Barlow, E. D., and Pochin, E. E. (1948). Clin. Sci., 6, 303.
2. Berry, C. M., Grundfest, H., and Hinsey, J. C. (1944). J. Neurophysiol., 7, 103.
3. Brain, W. R., Wright, A. D., and Wilkinson, M. (1947). Lancet, 1, 277.
4. M. S. (Phys. Med.);Carpendale, M.T.F.,1956
5. Cobb, W., and Marshall, J. (1954). J. Neurol. Neurosurg. Psvchiat., 17, 183.