@article{IVM_1970_11_a10,
     author = {P. P. Rybin},
     title = {The periodic solutions of differential equations in a~particular case},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {97--99},
     publisher = {mathdoc},
     number = {11},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1970_11_a10/}
}