1. Ward, W. E. F., “A History of the Gold Coast”, 81 (London, 1948). Palgrave, W. G., “Inter Guiana”, 161 (London, 1876).
2. Layrisse, M., Arends, T., and Dominguez Sisco, R., Acta Med. Venez., 3, 132 (1955). Layrisse, M., and Arends, T., Science, 123, 633 (1956).
3. Boyd, W. C., “Tabulae Biol.”, Hague, 17, 207 (1939). Mourant, A. E., “The Distribution of the Human Blood Groups” (Blackwell Scientific Pub., Oxford, 1954).
4. Acosta Saignes, M., “Estudios de Etnologia antigua de Venezuela” (Universidad Central de Venezuela, 1954). Hernandez de Alba, G., Bull. Bur. Amer. Ethnol., 4, 469 (1948).
5. Levine, P., Robinson, E. A., Layrisse, M., Arends, T., and Dominguez Sisco, R., Nature, 177, 40 (1956). Layrisse, M., and Arends, T., Blood (in the press).