1. Manual ofantenatalpathology and hygiene, Edinb;Ballantyne, J.W.,1902
2. Bonney, V., and Morton, H. J. S. (1938). Proc. roy. Soc. Med., 31, 1060.
3. Bourret and Lathoud (1912). Bull. Soc. Obstet. Gynec., Paris, 1, 499.
4. Browne, F. J. (1924). Med. Res. Council, Special Report Series No. 86, p. 65.
5. Bullard, E. A., and Plaut, A. (1926). 292.