@article{IM2_1981_16_3_a4,
     author = {V. V. Nikulin},
     title = {On arithmetic groups generated by reflections in {Lobachevskii} spaces},
     journal = {Izvestiya. Mathematics},
     pages = {573--601},
     year = {1981},
     volume = {16},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1981_16_3_a4/}
}