@article{DE_1981_17_8_a11,
     author = {E. E. Barbashina},
     title = {Necessary optimality conditions for systems of differential equations that are not solved with respect to the derivative},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1478--1480},
     publisher = {mathdoc},
     volume = {17},
     number = {8},
     year = {1981},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1981_17_8_a11/}
}