1. Barell, B. G. and Clark, B. F. S.: 1974,Handbook of Nucleic Acid Sequences, Joynson-Bruvveri Ltd., Oxford.
2. Crick, F. H. C.: 1966,J. Mol. Biol.,19, 584.
3. Crick, F. H. C.: 1968,J. Mol. Biol.,38, 367.
4. Crick, F. H. C., Griffith, J. S., and Orgel, L. E.: 1957,Proc. Nat. Acad. Sci. (U.S.A.) 43, 416.
5. Eigen, M.: 1973, in J. Mehra (ed.),The Physicist's Conception of Nature, D. Reidel Publishing Co., Boston, U.S.A.