@article{DE_1978_14_5_a18,
     author = {E. K. Ershov},
     title = {The dependence on the parameter of the structure of the solutions on a toroidal invariant surface},
     journal = {Differencialʹnye uravneni\^a},
     pages = {919--921},
     publisher = {mathdoc},
     volume = {14},
     number = {5},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_5_a18/}
}