@article{10_4153_CMB_2003_022_3,
     author = {Li, Chi-Kwong and Rodman, Leiba and \v{S}emrl, Peter},
     title = {Linear {Maps} on {Selfadjoint} {Operators} {Preserving} {Invertibility,} {Positive} {Definiteness,} {Numerical} {Range}},
     journal = {Canadian mathematical bulletin},
     pages = {216--228},
     year = {2003},
     volume = {46},
     number = {2},
     doi = {10.4153/CMB-2003-022-3},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2003-022-3/}
}