Comment on "A note on the construction of the Ermakov-Lewis invariant"
  We show that the basic results on the paper referred in the title [J. Phys. A: Math. Gen. v. 35 (2002) 5333-5345], concerning the derivation of the Ermakov invariant from Noether symmetry methods, are not new. 
F. Haas and J. Goedert