\begin{thebibliography}{}
\bibitem[Berleant\&Kuipers97]{Berleant97} D. Berleant y B.J. Kuipers.
 Qualitative and quantitative simulation: bridging the gap
{\it Artificial Intelligence} 95, pp. 215-255, 1997
\bibitem[Corliss95]{Corliss95} G.F. Corliss.
 Guaranteed error bounds for ordinary differential equations
{\it Theory of Numerics in Ordinary and Partial Differential Equations}. Oxford
University Press. 1995.
\bibitem[Kay96]{Kay96}H. Kay.
Refining imprecise models and their behaviors.
{Ph.D. Thesis} University of Texas (USA), 1996.
\bibitem[Kuipers94]{Kuipers94} B.J. Kuipers.
{\it Qualitative reasoning. Modeling and simulation with incomplete knowledge},
The MIT Press, Cambridge,Massachussetts 1994.
\bibitem[Vescovi {\it et al.} 95]{Vescovi95}M. Vescovi, A. Farquhar,
Y. Iwasaki. Numerical interval simulation: combined qualitative and quantitative
simulation to bound behaviors of non-monotonic systems.
{\it Proc. 14th Int. Joint Conference on Artificial Intelligence} pages 1806--1812,
Canada, 1995.
\end{thebibliography}