Abstract

References
1.
Enos
W F
Beyer
J C
Holmes
R H
. (1955 ) J. Amer. med. Ass.
158 , 912
2.
Franco
S C
Gerl
A J
Murphy
G T
. (1961 ) J. occup. Med.
3 , 13
3.
Friedberg
C K
Jaffe
H L
Pordy
L
Chesky
K
. (1962 ) Circulation
26 , 1254
4.
Hale
G
Dexter
D
Jefferson
K
Leatham
A
. (1966 ) Brit. Heart J.
28 , 40
5.
Master
A M
Rosenfeld
I
. (1964 ) J. Amer. med. Ass.
190 , 494
6.
Proudfit
W L
Shirey
E K
Sones
F M
Jr
(1966 ) Circulation
33 , 901
