@article{IM2_1975_9_2_a9,
     author = {V. I. Kolyada},
     title = {On imbedding in classes~$\varphi(L)$},
     journal = {Izvestiya. Mathematics},
     pages = {395--413},
     year = {1975},
     volume = {9},
     number = {2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1975_9_2_a9/}
}