@article{GDZPPN002323931, title = {On the Top Betti Number of Subgroups of SL(n,Z).}, journal = {Mathematische Annalen}, volume = {264}, year = {1983}, pages = {277-282}, zbl = {0505.20035}, url = {http://dml.mathdoc.fr/item/GDZPPN002323931} }
Ash, Avner. On the Top Betti Number of Subgroups of SL(n,Z).. Mathematische Annalen, Tome 264 (1983) pp. 277-282. http://gdmltest.u-ga.fr/item/GDZPPN002323931/