TY  - JOUR
AU  - Chi-Kwong Li
AU  - Yiu-Tung Poon
TI  - The joint essential numerical range of operators:
convexity and related results
JO  - Studia Mathematica
PY  - 2009
SP  - 91
EP  - 104
VL  - 194
IS  - 1
UR  - http://geodesic.mathdoc.fr/articles/10.4064/sm194-1-6/
DO  - 10.4064/sm194-1-6
LA  - en
ID  - 10_4064_sm194_1_6
ER  -