@article{IM_1991__104_1_143894,
     author = {Alexander Lubotzky and Avinoam Mann},
     title = {On groups of plolynomial subgroup growth.},
     journal = {Inventiones mathematicae},
     pages = {521--534},
     publisher = {mathdoc},
     volume = {104},
     number = {1},
     year = {1991},
     zbl = {0743.20040},
     url = {http://geodesic.mathdoc.fr/item/IM_1991__104_1_143894/}
}