@article{10_1017_S0017089500001476,
     author = {Dollinger, Michael B. and Oberai, Kirti K.},
     title = {On the spectrum of a linear operator},
     journal = {Glasgow mathematical journal},
     pages = {98--101},
     year = {1972},
     volume = {13},
     number = {2},
     doi = {10.1017/S0017089500001476},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500001476/}
}