70K05 Phase plane analysis, limit cycles
70K20 Stability
70K25 Free motions
70K28 Parametric resonances
70K30 Nonlinear resonances
70K40 Forced motions
70K42 Equilibria and periodic trajectories
70K43 Quasi-periodic motions and invariant tori
70K44 Homoclinic and heteroclinic trajectories
70K45 Normal forms
70K50 Bifurcations and instability
70K55 Transition to stochasticity (chaotic behavior) [See also 37D45]
70K60 General perturbation schemes
70K65 Averaging of perturbations
70K70 Systems with slow and fast motions
70K75 Nonlinear modes
70K99 None of the above, but in this section