@article{ELA_1998__3__a7,
     author = {Li, Chi-Kwong and Rodman, Leiba},
     title = {Shapes and computer generation of numerical ranges of {Krein} space operators},
     journal = {The electronic journal of linear algebra},
     pages = {31--47},
     publisher = {mathdoc},
     volume = {3},
     year = {1998},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ELA_1998__3__a7/}
}