Power output of push-push and N-push oscillators, what is approximate numbers?

[Terminator3]

Is there any way to approximately know power output of N-push oscillator at N-th even harmonic?
For multipliers there is fourier approach, what can be used here?

Thanks!

 

[BigBoss]

Harmonic levels are totally depended on nonlinearity of the circuit,especially active devices.Therefore nonlinearity in otherwords harmonic levels can not be calculated by hand.