@article{DE_1974_10_6_a4,
     author = {G. S. Osipenko},
     title = {The problems of {Frommer}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1015--1024},
     year = {1974},
     volume = {10},
     number = {6},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1974_10_6_a4/}
}