Abstract

Get full access to this article
View all access options for this article.
References
1.
Baird
D.
(1969 ). Combined Textbook of Obstetrics and Gynaecology . Edinburgh : Livingstone .
2.
Barber
B.
(1957 ). Social Stratification . New York : Harcourt Brace .
3.
Barker
D. J. P.
(1972 ). Practical Epidemiology . Edinburgh : Churchill Livingstone .
4.
Blalock
H. M.
Blalock
A. B.
(eds) (1968 ). Methodology in Social Research . New York : McGraw-Hill .
5.
Castle
W. M.
Saphire
K. E.
(1976 ). S. Afr. med. J. , 50 , 1143 .
6.
Siegel
S.
(1956 ). Non Parametric Statistics . Tokyo : McGraw-Hill .
7.
Nines
Spiral
(1969 ). (Form B) National Institute for Personnel Research . Johannesburg .
8.
Stevenson
T. H. C.
(1928 ). J. roy. stat. Soc. , 91 , 207 .
9.
Vernon
P. E.
(1969 ). Intelligence and Cultural Environment . London : Methuen .
