@article{DE_1981_17_9_a2,
     author = {S. N. Vassilyev},
     title = {The comparison method in systems {analysis.~I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1562--1573},
     publisher = {mathdoc},
     volume = {17},
     number = {9},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_9_a2/}
}