@article{SM_1968_5_4_a6,
     author = {V. A. Artamonov},
     title = {Admissible subgroups of a free product of $\Gamma$-operator groups with
},
     journal = {Sbornik. Mathematics},
     pages = {571--584},
     publisher = {mathdoc},
     volume = {5},
     number = {4},
     year = {1968},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1968_5_4_a6/}
}