@article{TRSPY_1988_185_a7,
     author = {A. K. Kerimov},
     title = {Sufficient conditions for optimality in an extremal problem with a~free boundary},
     journal = {Informatics and Automation},
     pages = {87--105},
     publisher = {mathdoc},
     volume = {185},
     year = {1988},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1988_185_a7/}
}