@article{MAN_1983__264_163787,
     author = {Avner Ash},
     title = {On the {Top} {Betti} {Number} of {Subgroups} of {SL(n,Z).}},
     journal = {Mathematische Annalen},
     pages = {277--282},
     publisher = {mathdoc},
     volume = {264},
     year = {1983},
     zbl = {0505.20035},
     url = {http://geodesic.mathdoc.fr/item/MAN_1983__264_163787/}
}