Abstract

References
1.
Graham
P A
, (1967 ) The Early Diagnosis of Visual Defects . Office of Health Economics . Early Diagnosis Papers, 2
2.
Langham
M E
, (1971 ) Proceedings of the Royal Society of Medicine
64 , 622
3.
van Zonneveld
R J
, (1955 ) Old Age in the Modern World . Livingstone , Edinburgh ; p 349
