%0 Journal Article %A Mohammad Ali Ardalani %T Numerical index with respect to an operator %J Studia Mathematica %D 2014 %P 165-171 %V 225 %N 2 %U http://geodesic.mathdoc.fr/articles/10.4064/sm225-2-3/ %R 10.4064/sm225-2-3 %G en %F 10_4064_sm225_2_3