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@article{MZM_2000_68_4_a15, author = {Yu. A. Aminov}, title = {On a problem of {Hopf}}, journal = {Matemati\v{c}eskie zametki}, pages = {637--640}, publisher = {mathdoc}, volume = {68}, number = {4}, year = {2000}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_2000_68_4_a15/} }
Yu. A. Aminov. On a problem of Hopf. Matematičeskie zametki, Tome 68 (2000) no. 4, pp. 637-640. http://geodesic.mathdoc.fr/item/MZM_2000_68_4_a15/