1. Dudgeon, J. A.: Communication presented to the Symposium on the Placenta, N. Y. Academy of Medicine, 6th March, 1964 (to he published in Journal of Paediatrics).
2. Dudgeon, J. A., N. R. Butler, andS. A. Plotkin: Brit. Med. J.2, 155 (1964).
3. Lundstr�m, R.: Acta Paediat. (Stockholm)51, Suppl. No. 133 (1962).
4. Manson, M. M., et al.: Reports on Publ. Hlth. and Med. Subjects No. 101. H. M. S. O. London 1960.
5. Plotkin, S. A., J. A. Dudgeon, andA. M. Ramsay: Brit. Med. J.2, 1296 (1963).