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@article{DAN_1987_294_2_a0, author = {A. A. Borisenko}, title = {On extremal properties of compact surfaces on nonpositive extrinsic curvature}, journal = {Doklady Akademii Nauk}, pages = {265--268}, publisher = {mathdoc}, volume = {294}, number = {2}, year = {1987}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1987_294_2_a0/} }
A. A. Borisenko. On extremal properties of compact surfaces on nonpositive extrinsic curvature. Doklady Akademii Nauk, Tome 294 (1987) no. 2, pp. 265-268. http://geodesic.mathdoc.fr/item/DAN_1987_294_2_a0/