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@article{DAN_1994_336_5_a1, author = {V. A. Kostin}, title = {On the solution of a problem associated with an abstract cosine}, journal = {Doklady Akademii Nauk}, pages = {584--586}, publisher = {mathdoc}, volume = {336}, number = {5}, year = {1994}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1994_336_5_a1/} }
V. A. Kostin. On the solution of a problem associated with an abstract cosine. Doklady Akademii Nauk, Tome 336 (1994) no. 5, pp. 584-586. http://geodesic.mathdoc.fr/item/DAN_1994_336_5_a1/