@article{SM_1988_59_2_a3,
     author = {A. V. Ostrovsky},
     title = {On a question of {L.} {V.~Keldysh} concerning the structure of {Borel} sets},
     journal = {Sbornik. Mathematics},
     pages = {317--337},
     year = {1988},
     volume = {59},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1988_59_2_a3/}
}