@article{GDZPPN002061139,
title = {Corners and Arithmetic Groups},
journal = {Commentarii mathematici Helvetici},
volume = {48},
year = {1973},
pages = {436-483},
zbl = {0274.22011},
url = {http://dml.mathdoc.fr/item/GDZPPN002061139}
}
Borel, A.; Serre, J-P. Corners and Arithmetic Groups. Commentarii mathematici Helvetici, Tome 48 (1973) pp. 436-483. http://gdmltest.u-ga.fr/item/GDZPPN002061139/