A few special chaotic systems without unstable equilibrium points have been investigated recently
Fractional-order and memristive nonlinear systems: Advances and applications
Chaotic systems are nonlinear dynamical systems which are sensitive to initial conditions, topologically mixing, and with dense periodic orbits
New Trends on Modeling, Design, and Control of Chaotic Systems
Nowadays, one of the most studied phenomena is chaos into the nonlinear dynamical systems.