@article{DE_2006_42_5_a0,
     author = {V. V. Amel'kin},
     title = {Strong isochronicity of the {Lienard} system},
     journal = {Differencialʹnye uravneni\^a},
     pages = {579--582},
     publisher = {mathdoc},
     volume = {42},
     number = {5},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2006_42_5_a0/}
}