1. Cooper, I. S. (1953). Science, 118, 193.
2. Cooper, I. S. (1954). Ibid., 119, 417.
3. -,-and Poloukhine, N. (1955). J. Amer. Geriat. Soc., 3, 839.
4. Fenelon, F. (1950). Rev. neurol. (Paris), 83, 437.
5. Guiot, G., and Brion, S. (1953). Ibid., 89, 578.