@article{01505958, title = {Spatial numerical ranges of elements of subalgebras of }, journal = {International Journal of Mathematics and Mathematical Sciences}, volume = {23}, year = {2000}, pages = {827-831}, doi = {10.1155/S0161171200003148}, zbl = {0970.46036}, language = {en}, url = {http://dml.mathdoc.fr/item/01505958} }
Takahasi, Sin-Ei. Spatial numerical ranges of elements of subalgebras of . International Journal of Mathematics and Mathematical Sciences, Tome 23 (2000) pp. 827-831. doi : 10.1155/S0161171200003148. http://gdmltest.u-ga.fr/item/01505958/