%0 Journal Article
%A Karel Leeuw
%T On the Adjoint Semigroup and Some Problems in the Theory of Approximation.
%J Mathematische Zeitschrift
%D 1960
%P 219-234
%V 73
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MZ_1960__73_169842/
%F MZ_1960__73_169842