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@article{AM2_1977__16_136693, author = {Marvin Marcus}, title = {Pencils of real symmetric matrices and the numerical range. {(Short} {Communication).}}, journal = {Aequationes mathematicae}, pages = {193--193}, publisher = {mathdoc}, volume = {16}, year = {1977}, url = {http://geodesic.mathdoc.fr/item/AM2_1977__16_136693/} }
Marvin Marcus. Pencils of real symmetric matrices and the numerical range. (Short Communication).. Aequationes mathematicae, Tome 16 (1977), p. 193. http://geodesic.mathdoc.fr/item/AM2_1977__16_136693/