@article{AL_2004_43_3_a1,
     author = {A. S. Morozov and V. G. Puzarenko},
     title = {$\Sigma${-Subsets} of {Natural} {Numbers}},
     journal = {Algebra i logika},
     pages = {291--320},
     publisher = {mathdoc},
     volume = {43},
     number = {3},
     year = {2004},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2004_43_3_a1/}
}