Physics Letters A · 1991 · 25 citations · 15 references
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More exact invariants for the time-dependent harmonic oscillator
John R. Ray, James L. Reid · Physics Letters A · 1979 · 194 citations
Nonlinear superposition law for generalized Ermakov systems
John R. Ray · Physics Letters A · 1980 · 96 citations
Dynamical invariants and time-dependent harmonic systems
H. J. Korsch · Physics Letters A · 1979 · 70 citations
On linearization of the Ermakov system
Chris Athorne, C. Rogers, U. Ramgulam et al. · Physics Letters A · 1990 · 67 citations