@article{DAN_1970_191_3_a8,
     author = {S. Sirota},
     title = {On the problem of the classification of filters},
     journal = {Doklady Akademii Nauk},
     pages = {533--536},
     publisher = {mathdoc},
     volume = {191},
     number = {3},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1970_191_3_a8/}
}