@article{JRAM_1992__427_153416,
     author = {Douglas L. Costa and Gordon E. Keller},
     title = {Radix redux: {Normal} subgroups of symplectic groups.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {51--106},
     publisher = {mathdoc},
     volume = {427},
     year = {1992},
     zbl = {0739.20023},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1992__427_153416/}
}