@article{IM2_1969_3_4_a8,
     author = {A. Yu. Ol'shanskii},
     title = {Varieties of finitely approximable groups},
     journal = {Izvestiya. Mathematics},
     pages = {867--877},
     year = {1969},
     volume = {3},
     number = {4},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1969_3_4_a8/}
}