@article{DE_1967_3_7_a2,
     author = {L. A. Cherkas},
     title = {Stability of a singular cycle in the critical case},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1060--1069},
     publisher = {mathdoc},
     volume = {3},
     number = {7},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1967_3_7_a2/}
}