@article{DE_1972_8_10_a15,
     author = {L. Ashchepkov},
     title = {On necessary conditions for high order optimality for singular controls of discrete systems},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1857--1867},
     publisher = {mathdoc},
     volume = {8},
     number = {10},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_10_a15/}
}