@article{10_1017_S0017089500005760,
     author = {Ch\={o}, Muneo and Dash, A. T.},
     title = {On the joint spectra of doubly commuting n-tuples of semi-normal operators},
     journal = {Glasgow mathematical journal},
     pages = {47--50},
     year = {1985},
     volume = {26},
     number = {1},
     doi = {10.1017/S0017089500005760},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500005760/}
}