@article{SIGMA_2005_1_a17,
     author = {P. G. L. Leach and A. Karasu (Kalkanli) and M. C. Nucci and K. Andriopoulos},
     title = {Ermakov's {Superintegrable} {Toy} and {Nonlocal} {Symmetries}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2005},
     volume = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2005_1_a17/}
}