@article{IVM_1966_1_a12,
     author = {K. E. Malkin},
     title = {Conditions for the center for a~class of differential equations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {104--114},
     publisher = {mathdoc},
     number = {1},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1966_1_a12/}
}