@article{DA_1990_30_a5,
     author = {K. S. Musabekov},
     title = {A necessary condition for optimality in a problem with a phase constraint},
     journal = {Diskretnyj analiz i issledovanie operacij},
     pages = {46--56},
     publisher = {mathdoc},
     number = {30},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DA_1990_30_a5/}
}