@article{DE_1999_35_10_a10,
     author = {A. S. Platonov},
     title = {On the existence of a linear {Pfaffian} system with an arbitrary countable lower characteristic set},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1382--1386},
     publisher = {mathdoc},
     volume = {35},
     number = {10},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1999_35_10_a10/}
}