Appendix 1: 3.3.1: Small damping, no driving force
Appendix 2: 3.3.2: Nonlinear Oscillations and chaotic motion
Appendix 3: 3.3.3.1: Bistable response of the Duffing oscillator
Appendix 4a: 3.3.3.2: Perturbation series solution of the Duffing oscillator up to lambda^2-terms
Appendix 4b: 3.3.3.2: Perturbation series solution of the Duffing oscillator up to lambda^5-terms
Appendix 5: 4.5: Interaction of 2 solitons (analytical)