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@article{FAA_1975_9_1_a4, author = {G. A. Isaev}, title = {Numerical range of operator pencils and keldysh multiple completeness}, journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a}, pages = {31--34}, publisher = {mathdoc}, volume = {9}, number = {1}, year = {1975}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/FAA_1975_9_1_a4/} }
G. A. Isaev. Numerical range of operator pencils and keldysh multiple completeness. Funkcionalʹnyj analiz i ego priloženiâ, Tome 9 (1975) no. 1, pp. 31-34. http://geodesic.mathdoc.fr/item/FAA_1975_9_1_a4/