1. Ahmed, E. (1990). U.A.E. University preprint.
2. Barnesly, M. (1988).Fractals Everywhere, Academic Press.
3. Devany, R. (1989).An Introduction to Chaotic Dynamical Systems, Addison-Wesley.
4. Swan, G. W. (1990).Mathematical Biosciences,101, 237.
5. West, B. J. (1990).Fractals and Chaos in Medicine, World Scientific, Singapore.