@article{MZM_1997_61_6_a11,
     author = {V. Jankovic},
     title = {Necessary conditions for an extremum in the calculus of variations with nonsmooth phase variables},
     journal = {Matemati\v{c}eskie zametki},
     pages = {922--930},
     publisher = {mathdoc},
     volume = {61},
     number = {6},
     year = {1997},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1997_61_6_a11/}
}