TY  - JOUR
AU  - Erik Balslev
TI  - Perturbation of Ordinary Differential Operators.
JO  - Mathematica Scandinavica
PY  - 1962
SP  - 131
EP  - 148
VL  - 11
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MS2_1962__11_165821/
ID  - MS2_1962__11_165821
ER  -