REFERENCES
- Clayton, Y. M. (1969). Transactions of the Ophthalmological Societies of the United Kingdom, 89, 837–844.
- Richards, A. B., Jones, B. R., Whitwell, J. & Clayton, Y. M. (1969). Transactions of the Ophthalmological Societies of the United Kingdom, 89, 867–885.
- Richards, W. H. G. & Maples, B. K. (1979). Annals of Tropical Medicine and Parasitology, 73, 99–108.
- Trager, W. & Jensen, J. B. (1976). Science, 193, 673–675.