@article{SM_1969_9_2_a1,
     author = {M. S. Burgin},
     title = {Some properties of generalized free products and the imbedding of amalgams of groups},
     journal = {Sbornik. Mathematics},
     pages = {155--170},
     publisher = {mathdoc},
     volume = {9},
     number = {2},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_9_2_a1/}
}