@article{NUMA_1972__20_132184,
     author = {F. Chatelin},
     title = {Approximation du spectre d'un operateur linearie; application aux operateurs differentiels elliptiqes non autoadjoints.},
     journal = {Numerische Mathematik},
     pages = {193--204},
     publisher = {mathdoc},
     volume = {20},
     year = {1972},
     zbl = {0268.65070},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1972__20_132184/}
}