@article {598,
	title = {Dynamical symmetries and the Ermakov invariant},
	journal = {Phys. Lett. A},
	volume = {279},
	year = {2001},
	pages = {181},
	attachments = {https://professor.ufrgs.br/sites/default/files/fernando-haas/files/dynamical_symmetries.pdf},
	author = {F. Haas and J. Goedert}
}
