1. Response of self-excited oscillators to multifrequency excitations;Asfar,1980
2. Response of self-excited oscillators to multifrequency excitations, II;Asfar,1980
3. Nonlinear Oscillations;Nayfeh,1979
4. Perturbation Methods;Nayfeh,1973
5. Introduction to Perturbation Techniques;Nayfeh,1981