@article{ZNSL_1976_60_a0,
     author = {A. P. Beltiukov},
     title = {An iterative description of the class $\varepsilon^1$ of {Grzegorczyk's} hierarchy},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {3--14},
     publisher = {mathdoc},
     volume = {60},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1976_60_a0/}
}