@article{VMUMM_2013_6_a12,
     author = {V. M. Budanov},
     title = {On a nonlinear isochronous system},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {59--63},
     publisher = {mathdoc},
     number = {6},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2013_6_a12/}
}