@article{10_4153_CJM_1986_057_x,
     author = {McDonald, G. and Sundberg, C.},
     title = {On the {Spectra} of {Unbounded} {Subnormal} {Operators}},
     journal = {Canadian journal of mathematics},
     pages = {1135--1148},
     year = {1986},
     volume = {38},
     number = {5},
     doi = {10.4153/CJM-1986-057-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1986-057-x/}
}