@article{DE_1985_21_6_a26,
     author = {S. A. Mazanik},
     title = {On an approximating sequence},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1089--1091},
     publisher = {mathdoc},
     volume = {21},
     number = {6},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1985_21_6_a26/}
}