@article{IVM_1981_6_a6,
     author = {A. T. Nazmutdinov and I. Kh. Mudarisov},
     title = {Limit cycles of a~class of nonlinear differential equations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {39--42},
     year = {1981},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1981_6_a6/}
}