%0 Journal Article %A Bernard Morrel %A Paul Muhly %T Centered operators %J Studia Mathematica %D 1974 %P 251-263 %V 51 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/articles/10.4064/sm-51-3-251-263/ %R 10.4064/sm-51-3-251-263 %G en %F 10_4064_sm_51_3_251_263