@article{MZM_2008_84_4_a2,
     author = {I. I. Batyrshin},
     title = {Relative {Enumerability} in {Ershov's} {Hierarchy}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {506--515},
     publisher = {mathdoc},
     volume = {84},
     number = {4},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2008_84_4_a2/}
}