@article{RSM_2001__59_4_125135,
     author = {Schrohe, E. and Boggiatto, P.},
     title = {Characterization, spectral invariance and the {Fredholm} property of multi-quasi-elliptic operators.},
     journal = {Rendiconti del seminario matematico},
     pages = {229--242},
     publisher = {mathdoc},
     volume = {59},
     number = {4},
     year = {2001},
     zbl = {1072.47521},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RSM_2001__59_4_125135/}
}