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@article{DE_1975_11_7_a21, author = {A. N. Kochubei}, title = {The expansion in root vectors of abstract differential operators}, journal = {Differencialʹnye uravneni\^a}, pages = {1341--1342}, publisher = {mathdoc}, volume = {11}, number = {7}, year = {1975}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1975_11_7_a21/} }
A. N. Kochubei. The expansion in root vectors of abstract differential operators. Differencialʹnye uravneniâ, Tome 11 (1975) no. 7, pp. 1341-1342. http://geodesic.mathdoc.fr/item/DE_1975_11_7_a21/