@article{TM_2023_322_a16,
     author = {D. V. Treschev},
     title = {On {Isochronicity}},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {206--232},
     publisher = {mathdoc},
     volume = {322},
     year = {2023},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_2023_322_a16/}
}