@article{DE_1975_11_2_a22,
     author = {I. P. Martynov},
     title = {A generalization of a theorem of {H.} {Wittich}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {388--389},
     publisher = {mathdoc},
     volume = {11},
     number = {2},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1975_11_2_a22/}
}