Abstract
References
1.
Emerson
P A
Heath
G
Tomknis
J G
. (1961 ) Brit. med. J.
ii , 148 .
2.
Hess
E V
MacDonald
N
. (1954 ) Lancet
ii , 132 .
3.
Middlemiss
H
. (1961 ) Tropical Radiology , London .
4.
Springett
V H
Adams
T C S
Costa
T B
Fleming
M
. (1958 ) Brit. J. prev. soc. Med.
12 , 135 .
5.
Stevenson
D K
. (1962 ) Brit. med. J.
i , 1382 .