@article{IVM_2009_8_a9,
     author = {M. T. Teryokhin},
     title = {The limit cycles of a~second-order system of differential equations: the method of small forms},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {73--82},
     year = {2009},
     number = {8},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2009_8_a9/}
}