@article{DE_1989_25_9_a27,
     author = {V. I. Fomin},
     title = {Small perturbations of a singular differential equation with a constant unbounded operator coefficient},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1629--1630},
     publisher = {mathdoc},
     volume = {25},
     number = {9},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_9_a27/}
}