@article{AL_1990_29_4_a0,
     author = {N. V. Beliakin},
     title = {Effective hierarchies},
     journal = {Algebra i logika},
     pages = {385--397},
     publisher = {mathdoc},
     volume = {29},
     number = {4},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1990_29_4_a0/}
}