@article{10_1007_s10587_012_0024_7,
     author = {Jahedi, Khadijeh and Yousefi, Bahmann},
     title = {Numerical range of operators acting on {Banach} spaces},
     journal = {Czechoslovak Mathematical Journal},
     pages = {495--503},
     publisher = {mathdoc},
     volume = {62},
     number = {2},
     year = {2012},
     doi = {10.1007/s10587-012-0024-7},
     mrnumber = {2990189},
     zbl = {1259.47009},
     language = {en},
     url = {https://geodesic-test.mathdoc.fr/articles/10.1007/s10587-012-0024-7/}
}