@article{SM_2007_198_3_a1,
     author = {G. E. Ivanov},
     title = {A criterion of  smooth generating sets},
     journal = {Sbornik. Mathematics},
     pages = {343--368},
     publisher = {mathdoc},
     volume = {198},
     number = {3},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2007_198_3_a1/}
}