@article{10_1017_S0017089500006984,
     author = {Rudol, K.},
     title = {The spectrum of orthogonal sums of subnormal pairs},
     journal = {Glasgow mathematical journal},
     pages = {11--15},
     year = {1988},
     volume = {30},
     number = {1},
     doi = {10.1017/S0017089500006984},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500006984/}
}