References
- Population Reference Bureau, Inc. Population Bulletin, USA. Washington, DC 1989
- Kara Jose N, Contreras F, Campos M, et al. Populational study on visual selection and surgical intervention to reduce the blindness caused by cataract in campinas– Brasil and Chimbote–Peru. Arquivos Brasileiros de Oftalmo-logia 1989; 4: 91–96