@article{DE_1987_23_4_a8,
     author = {A. S. Matveev},
     title = {On the necessary conditions for an extremum in an optimal control problem with phase constraints},
     journal = {Differencialʹnye uravneni\^a},
     pages = {629--640},
     publisher = {mathdoc},
     volume = {23},
     number = {4},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_4_a8/}
}