@article{IVM_2021_8_a7,
     author = {M. M. Arslanov and I. I. Batyrshin and M. M. Yamaleev},
     title = {$CEA$ operators and the {Ershov} hierarchy},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {72--79},
     publisher = {mathdoc},
     number = {8},
     year = {2021},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2021_8_a7/}
}