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@article{DAN_1989_307_5_a1, author = {S. V. Buyalo}, title = {Three-dimensional manifolds of nonpositive curvature containing}, journal = {Doklady Akademii Nauk}, pages = {1037--1040}, publisher = {mathdoc}, volume = {307}, number = {5}, year = {1989}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1989_307_5_a1/} }
S. V. Buyalo. Three-dimensional manifolds of nonpositive curvature containing. Doklady Akademii Nauk, Tome 307 (1989) no. 5, pp. 1037-1040. http://geodesic.mathdoc.fr/item/DAN_1989_307_5_a1/