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@article{DAN_1966_170_1_a7, author = {M. G. Krein and Yu. L. Shmul'yan}, title = {A class of operators in a space with an indefinite metric}, journal = {Doklady Akademii Nauk}, pages = {34--37}, publisher = {mathdoc}, volume = {170}, number = {1}, year = {1966}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1966_170_1_a7/} }
M. G. Krein; Yu. L. Shmul'yan. A class of operators in a space with an indefinite metric. Doklady Akademii Nauk, Tome 170 (1966) no. 1, pp. 34-37. http://geodesic.mathdoc.fr/item/DAN_1966_170_1_a7/