1. Theory of oscillators;Andronov,1965
2. Oscillations in systems with relay feedback.;Åström,1993
3. Automatic tuning of simple regulators with specifications on phase and amplitude margins.;Åström;Automatica,1984
4. Nonlinear Control Engineering Describing Function Analysis and Design;Atherton,1975
5. SUNS: the Sussex University nonlinear control systems software.;Atherton,1985