@article{DE_1988_24_6_a1,
     author = {A. I. Astrovskii},
     title = {A method for solving an observation-estimation problem in linear nonstationary systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {929--935},
     publisher = {mathdoc},
     volume = {24},
     number = {6},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1988_24_6_a1/}
}