1. BENNETT, F. (1962). Lancet, 2, 726.
2. CORRIGAN, M. J., GILKES, M. J., and ROBERTS, D. ST. CLAIR (1962). Brit. med. J., 2, 304.
3. DAVIDSON, S. I. (1962). Lancet, 2, 1326.
4. GUNDERSEN, T. (1936). Arch. Ophthal. (Chicago), 15, 225.
5. KAUFMAN, H. E., and MALONEY, E. D. (1962). Ibid., 68, 396.