Voir la notice de l'article provenant de la source Math-Net.Ru
@article{AA_1989_1_3_a3, author = {S. V. Buyalo}, title = {Closed geodesics on 2-dimensional orbifolds of nonpositive curvature}, journal = {Algebra i analiz}, pages = {89--109}, publisher = {mathdoc}, volume = {1}, number = {3}, year = {1989}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/AA_1989_1_3_a3/} }
S. V. Buyalo. Closed geodesics on 2-dimensional orbifolds of nonpositive curvature. Algebra i analiz, Tome 1 (1989) no. 3, pp. 89-109. http://geodesic.mathdoc.fr/item/AA_1989_1_3_a3/