1. The Stability of Nonlinear Systems with a Nonunique Equilibrium State;Gelig,1987
2. Lyapunov-like solutions for stability problem of the most general stationing Lurie–Postnikov systems;Grujic;Internat. J. Systems Sci.,1981
3. Stability of Nonlinear Control Systems;Lefschetz,1965
4. Absolute stability of time lag system;Li;Acta Math. Sinica,1963
5. Frequency Domain Criteria for Absolute Stability;Narendra,1973