1. Aastveit, K. (1961). Meld. Norg. Landbr. Høisk., 40 (pt. 2, report 23), 1–112.
2. Aastveit, K. (1964). Genetics, 49, 159–164.
3. Adams, M.W. and Grafius, J.E. (1971). Crop Sci., II, 33–35.
4. Aksel, R. and Johnson, L.P.V. (1961). Can. J. Genet. Cytol., 3, 242–259.
5. Allard, R.W. (1960). Principles of Plant Breeding. New York: Wiley.