@article{10_4153_CJM_1970_017_7,
     author = {Putnam, C. R.},
     title = {The {Spectra} of {Semi-Normal} {Singular} {Integral} {Operators}},
     journal = {Canadian journal of mathematics},
     pages = {134--150},
     year = {1970},
     volume = {22},
     number = {1},
     doi = {10.4153/CJM-1970-017-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1970-017-7/}
}