1. Golubitsky, M., Stewart, I., and Schaeffer, D. G., Singularities and Groups in Bifurcation Theory, Vol. 1, Springer-Verlag, New York, 1982.
2. Poston, T. and Stewart, J., Catastrophe Theory and Its Applications, Pitman, London, 1978.
3. Thompson, J. M. T. and Hunt, G. W., A General Theory of Elastic Stability, Wiley, London, 1973.
4. Thompson, J. M. T. and Hunt, G. W., Elastic Instability Phenomena, Wiley, Chichester, 1984.
5. Korn, G. A. and Korn, T. M., Mathematical Handbook for Engineers, 2nd edn., McGraw-Hill, New York, 1968.