Abstract
References
1.
Hamlin
R H J
. (1952 ) Lancet
i , 64
2.
Hutton
M M
. (1964 ) Obstet. Gynec.
24 , 396
3.
MacRae
D J
. (1958 ) Brit. med. J.
ii , 107
4.
Stewart-Hess
C H
Green
T H H
. (1962 ) Brit. med. J.
ii , 1115