@article{DAN_1990_315_3_a0,
     author = {A. V. Arutyunov},
     title = {Higher-order conditions in abnormal extremal problems with},
     journal = {Doklady Akademii Nauk},
     pages = {521--525},
     publisher = {mathdoc},
     volume = {315},
     number = {3},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1990_315_3_a0/}
}