@article{MZM_2002_72_1_a7,
     author = {D. V. Osin},
     title = {Elementary {Classes} of {Groups}},
     journal = {Matemati\v{c}eskie zametki},
     pages = {84--93},
     publisher = {mathdoc},
     volume = {72},
     number = {1},
     year = {2002},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2002_72_1_a7/}
}