@article{AL_2015_54_4_a2,
     author = {S. S. Ospichev},
     title = {Friedberg numberings in the {Ershov} hierarchy},
     journal = {Algebra i logika},
     pages = {444--462},
     publisher = {mathdoc},
     volume = {54},
     number = {4},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2015_54_4_a2/}
}