Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MAT_1974_18_6_a1, author = {G. Harder}, title = {A {Gauss--Bonnet} formula for discrete arithmetically defined groups}, journal = {Matematika}, pages = {20--55}, publisher = {mathdoc}, volume = {18}, number = {6}, year = {1974}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MAT_1974_18_6_a1/} }
G. Harder. A Gauss--Bonnet formula for discrete arithmetically defined groups. Matematika, Tome 18 (1974) no. 6, pp. 20-55. http://geodesic.mathdoc.fr/item/MAT_1974_18_6_a1/