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@article{DAN_1971_201_1_a10, author = {V. S. Shulman}, title = {On algebras of operators in a space with indefinite metric of type $\Pi_1$}, journal = {Doklady Akademii Nauk}, pages = {44--47}, publisher = {mathdoc}, volume = {201}, number = {1}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1971_201_1_a10/} }
V. S. Shulman. On algebras of operators in a space with indefinite metric of type $\Pi_1$. Doklady Akademii Nauk, Tome 201 (1971) no. 1, pp. 44-47. http://geodesic.mathdoc.fr/item/DAN_1971_201_1_a10/