1. J.R.S. FINCHAM, Genetic complementation, Benjamin Inc. New York, Amsterdam (1966) 138 pp.
2. J.A. ROPER and R.H. PRITCHARD, Nature 175 (1955) 639.
3. S. BENZER, The chemical basis of heredity, Johns Hopkins Press, Baltimore (1958) 70
4. N. NASHED, Molec. Gen. Genetics 102 (1968) 285.
5. M.E. CASE and N.H. GILES, Proc. Nat. Acad. Sci., 46 (1960) 659.