1. Cohen, A. S., Boyd, W. C., Goldwasser, S., Cathcart, E. S., and Heisler, M., Nature, 200, 1215 (1963).
2. Hartmann, O. (personal communication, 1949), quoted by Race, R. R., and Sanger, Ruth, Blood Groups in Man, first ed. (Blackwell, Oxford, 1950).
3. Hartmann, O., and Lundevall, J. U., Blood Group Distribution in Norway, with Special Regard to the MN and OA1A2B System (Norske Vidensk. Akad., Oslo, 1944).
4. Kornstad, L. (unpublished observations, 1964).