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@article{DAN_1972_203_2_a5, author = {V. K. Ionin}, title = {Isoperimetric inequalities in simply connected {Riemann} spaces of nonpositive curvature}, journal = {Doklady Akademii Nauk}, pages = {282--284}, publisher = {mathdoc}, volume = {203}, number = {2}, year = {1972}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1972_203_2_a5/} }
V. K. Ionin. Isoperimetric inequalities in simply connected Riemann spaces of nonpositive curvature. Doklady Akademii Nauk, Tome 203 (1972) no. 2, pp. 282-284. http://geodesic.mathdoc.fr/item/DAN_1972_203_2_a5/