1. M. R. Rose,Evolutionary Theory of Aging (Oxford University Press, Oxford, 1991).
2. D. Stauffer,Braz. J. Phys. (1994).
3. D. Stauffer and N. Jan, St. Francis Xavier University preprint (1993);
4. T. S. Ray,J. Stat. Phys. 74:929 (1994);
5. N. Jan,J. Stat. Phys., in press (1994).