1. Buttle, G. A. H., and Khayyal, M. T., Nature, 194, 780 (1962).
2. Standen, O. D., Trans. Roy. Soc. Trop. Med. Hyg., 49, 416 (1955).
3. Berberian, D. A., Dennis, E. W., and Freele, H. W., Congn. Intern. Med. trop. et du Paludisme, Fifth Istanbul Communic., 2, 292–305 (1954).
4. Pena de Grimaldo, E., and Kershaw, W. E., Ann. Trop. Med. Parasit., 55, 107 (1961).