@article{IM2_1985_25_2_a1,
     author = {R. I. Grigorchuk},
     title = {Degrees of growth of finitely generated groups, and the theory of invariant means},
     journal = {Izvestiya. Mathematics },
     pages = {259--300},
     publisher = {mathdoc},
     volume = {25},
     number = {2},
     year = {1985},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1985_25_2_a1/}
}