1. Aghannan, N. and P. Rouchon (2002). On invariant asymptotic observers. In: Proceedings of the 41st IEEE Conference on Decision and Control. Vol. 2. pp. 1479-1484.
2. Arnold, V. (1976). Méthodes Mathématiques de la Mécanique Classique. Mir Moscou.
3. Nonholonomic mechanical systems with symmetry;Bloch;Arch. Rational Mech. Anal,1996
4. Control and Observer Design for Nonlinear Finite and Infinite Dimensional Systems. Chap. On Invariant Observers, pp. 53–66 Number 322;Bonnabel,2005
5. Bonnabel, S., Ph. Martin and P. Rouchon (2006) Invariant asymptotic observers. Accepted for publication in IEEE AC. http://arxiv.org/abs/math.OC/0612193.