@article{ZNSL_1997_240_a11,
     author = {T. V. Nagnibeda},
     title = {An estimate from above of spectral radii of random walks on surface groups},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {154--165},
     year = {1997},
     volume = {240},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1997_240_a11/}
}