@article{MAT_1970_14_2_a6,
     author = {D. Blackwell},
     title = {On stationary policies},
     journal = {Matematika},
     pages = {155--159},
     publisher = {mathdoc},
     volume = {14},
     number = {2},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MAT_1970_14_2_a6/}
}