Sw. Qian et al., Ermakov invariant and the general solution for a damped harmonic, oscillator with a force quadratic in velocity, J PHYS A, 34(27), 2001, pp. 5613-5617
This paper makes a generalization of the Ermakov system to obtain the Ermak
ov invariant for the case of a variable mass and variable frequency oscilla
tor with a force quadratic in velocity, and hence find the general solution
of a time dependent damped harmonic oscillator with a force quadratic in v
elocity.