The Method of Multiple Scales: Asymptotic Solutions and Normal Forms for Nonlinear Oscillatory Problems.

Nestor E. Sanchez The Method of Multiple Scales: Asymptotic Solutions and Normal Forms for Nonlinear Oscillatory Problems. 245-252 1996 21 J. Symb. Comput. 2 db/journals/jsc/jsc21.html#Sanchez96