@article{SM_1969_8_4_a3,
     author = {A. L. Shmel'kin},
     title = {On free products of groups},
     journal = {Sbornik. Mathematics},
     pages = {593--597},
     publisher = {mathdoc},
     volume = {8},
     number = {4},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_8_4_a3/}
}