1. Apley, J. (1951). Bristol med.-chir. J., 68, 124. Keith,J. D. (1951). In Modern trends inPaediatrics. ed. Parsons, L.
2. Naish, J. M. and Apley, J. (1951). Archives of Disease in Childhood, 26, 134.
3. Price, R. Kemball (1949). Brit. med. J., 1, 515.
4. Robinson, S. J., Aggeler, D. M. and Daniloff, G. T. (1948). J.