@article{DE_1985_21_1_a9,
     author = {V. V. Kornienko},
     title = {The spectrum of irregular operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {65--77},
     year = {1985},
     volume = {21},
     number = {1},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1985_21_1_a9/}
}