@article{SM_2004_195_1_a6,
     author = {P. V. Tumarkin},
     title = {Maximum-rank root subsystems of hyperbolic root systems},
     journal = {Sbornik. Mathematics},
     pages = {121--134},
     publisher = {mathdoc},
     volume = {195},
     number = {1},
     year = {2004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2004_195_1_a6/}
}