@article{AL_1994_33_3_a5,
     author = {U. U. Umirbaev},
     title = {On {Schreier} varieties of algebras},
     journal = {Algebra i logika},
     pages = {317--340},
     publisher = {mathdoc},
     volume = {33},
     number = {3},
     year = {1994},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1994_33_3_a5/}
}