@article{DAN_1992_322_5_a5,
     author = {T. K. Melikov},
     title = {Recurrence conditions for the optimality of singular controls in},
     journal = {Doklady Akademii Nauk},
     pages = {843--846},
     publisher = {mathdoc},
     volume = {322},
     number = {5},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_322_5_a5/}
}