%0 Journal Article
%A Erik Balslev
%T Perturbation of Ordinary Differential Operators.
%J Mathematica Scandinavica
%D 1962
%P 131-148
%V 11
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MS2_1962__11_165821/
%F MS2_1962__11_165821