@article{DE_1979_15_3_a19,
     author = {A. V. Knyazev},
     title = {The method of frozen coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {551--552},
     publisher = {mathdoc},
     volume = {15},
     number = {3},
     year = {1979},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1979_15_3_a19/}
}