@article{VNGU_2015_15_1_a4,
     author = {S. S. Ospichev},
     title = {Computable families of sets in {Ershov} hierarchy without principal numberings},
     journal = {Sibirskij \v{z}urnal \v{c}istoj i prikladnoj matematiki},
     pages = {54--62},
     publisher = {mathdoc},
     volume = {15},
     number = {1},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VNGU_2015_15_1_a4/}
}