TY  - JOUR
AU  - W. Hansen
AU  - Z. Ma
TI  - Perturbation by differences of unbounded potentials.
JO  - Mathematische Annalen
PY  - 1990
SP  - 553
EP  - 570
VL  - 287
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MAN_1990__287_1_164705/
ID  - MAN_1990__287_1_164705
ER  -