@article{DE_1994_30_9_a2,
     author = {N. G. Dokuchaev},
     title = {Existence of optimal controls and necessary conditions for optimality for partially observable diffusion processes},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1498--1507},
     year = {1994},
     volume = {30},
     number = {9},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1994_30_9_a2/}
}