1. Sickel, W., Lippman, H. G., Haschke, W., and Baumann, C., Ber. dtsch. Ophthal. Ges., 63, 316 (1961).
2. Sickel, W., Science, 148, 648 (1965); and in Clinical Electroretinography (edit. by Burian, H., and Jacobson, J.), 115 (Pergamon Press, Oxford and New York, 1966).
3. Ames, A., and Gurian, B. S., Arch. Ophthal., 70, 837 (1963).
4. Ames, A., in Biochemistry of the Retina (edit. by Graymore, C. N.) 22 (Academic Press, London and New York, 1965).
5. Rushton, W. A. H., J. Physiol., 156, 193 (1961).