%0 Journal Article
%A Chi-Kwong Li
%A Nung-Sing Sze
%T Product of operators and  numerical range preserving maps
%J Studia Mathematica
%D 2006
%P 169-182
%V 174
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/articles/10.4064/sm174-2-4/
%R 10.4064/sm174-2-4
%G en
%F 10_4064_sm174_2_4