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@article{MZM_1992_51_5_a19, author = {A. S. Krantsberg}, title = {On a generalization of the bessel inequality}, journal = {Matemati\v{c}eskie zametki}, pages = {149--150}, publisher = {mathdoc}, volume = {51}, number = {5}, year = {1992}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1992_51_5_a19/} }
A. S. Krantsberg. On a generalization of the bessel inequality. Matematičeskie zametki, Tome 51 (1992) no. 5, pp. 149-150. http://geodesic.mathdoc.fr/item/MZM_1992_51_5_a19/