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@article{MAN_1977__227_162974, author = {Palle E.T. Jorgensen}, title = {Approximately {Invariant} {Subspaces} for {Unbounded} {Linear} {Operators.} {II.}}, journal = {Mathematische Annalen}, pages = {177--182}, publisher = {mathdoc}, volume = {227}, year = {1977}, zbl = {0345.47023}, url = {http://geodesic.mathdoc.fr/item/MAN_1977__227_162974/} }
Palle E.T. Jorgensen. Approximately Invariant Subspaces for Unbounded Linear Operators. II.. Mathematische Annalen, Tome 227 (1977), pp. 177-182. http://geodesic.mathdoc.fr/item/MAN_1977__227_162974/