@article{IVM_1993_12_a2,
     author = {N. G. Bil'chenko and K. G. Garaev},
     title = {On the existence of the first integral in an optimal problem with distributed parameters},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {31--34},
     publisher = {mathdoc},
     number = {12},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1993_12_a2/}
}