Time-dependent Lagrangians for forced systems and the Euler-Lagrange equations

[StuckOnZero]

I'm looking for a good reference work on time-dependent Lagrangians. For example, the Lagrangian and resultant Euler-Lagrange equations for a forced harmonic oscillator. All the classical textbooks just skip over this subject area. Obviously the system is non-energy conserving. In deriving the E-L equations one has to add a partial wrt T. I am looking to solve some electron trajectory problems when there is a weak oscillating external E-field.
-Thanks

 

[Bill_K]

Your best bet will be a book on applied mechanics, either celestial mechanics, tokamak or particle accelerators.