1. The evolution of metabolic function, R. P. Mortlock, ed., 330 pp. CRC Press (1992).
2. W. F. Loomis, Four billion years, an essay on the evolution of genes and organisms, 286 pp., Sinauer Associates, Inc. Publishers, Sunderland, MA (1988).
3. N. H. Horowitz, Proc. Natl. Acad. Sci. US., 31, 153–157 (1945).
4. N. H. Horowitz, in Evolving Genes and proteins, V. Bryson and H. J. Vogel, eds., 16–23, Academic Press, New York (1965).
5. M. Ycas, J. Theoret. Biol., 44, 145–160 (1974).