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@article{MZM_1971_9_2_a7, author = {V. N. Polyakov}, title = {A problem concering characteristic functions of linear operators}, journal = {Matemati\v{c}eskie zametki}, pages = {171--180}, publisher = {mathdoc}, volume = {9}, number = {2}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1971_9_2_a7/} }
V. N. Polyakov. A problem concering characteristic functions of linear operators. Matematičeskie zametki, Tome 9 (1971) no. 2, pp. 171-180. http://geodesic.mathdoc.fr/item/MZM_1971_9_2_a7/