@article{10_4153_CMB_1974_125_5,
     author = {Lin, C.-S.},
     title = {Boundary {Points} of the {Numerical} {Range} of an {Operator}},
     journal = {Canadian mathematical bulletin},
     pages = {689--692},
     year = {1975},
     volume = {17},
     number = {5},
     doi = {10.4153/CMB-1974-125-5},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1974-125-5/}
}