@article{JRAM_1966__224_150763,
     author = {Arnold Borel},
     title = {Density and maximality of arithmetic subgroups.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {78--89},
     publisher = {mathdoc},
     volume = {224},
     year = {1966},
     zbl = {0158.03105},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1966__224_150763/}
}