@article{AL_1990_29_3_a2,
     author = {A. N. Degtev},
     title = {Recursive-combinatorial properties of subsets of natural},
     journal = {Algebra i logika},
     pages = {303--314},
     publisher = {mathdoc},
     volume = {29},
     number = {3},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1990_29_3_a2/}
}