I recently looked at the reference in an article I am reading, and subsequently checked "Oscillations and Waves in Linear and Nonlinear Systems" my Rabinovihc and Trubetskov from the local library. https://www.amazon.com/Oscillations-Waves-Nonlinear-Mathematics-Applications/dp/0792304454 Great book, but unfortunately as a first year graduate student, it is hard for me to understand. I have looked at this forum: http://physics.stackexchange.com/qu...extbook-to-learn-about-waves-and-oscillations And looked at all the textbooks there, and they are all fantastic, but introductory. Can anyone suggest a book that is intermediate between these two extremes? At the moment, I want to develop a model for synchronizing two non-linear oscillators. Been done before, but it is a useful exercise.