1. A multiplicative ergodic theorem: Lyapunov characteristic numbers for dynamical systems;Oseledec;Trans. Moscow Math. Soc.,1968
2. Ergodic theory of chaos and strange attractors;Eckmann;Reviews of Modern Physics,1985
3. At least one Lyapunov exponent vanishes if the trajectory of an attractor does not contain a fixed point;Haken;Phys. Letters A,1983