TY  - JOUR
AU  - W. Hansen
TI  - Perturbation of Harmonic Spaces and Construction of Semigroups.
JO  - Inventiones mathematicae
PY  - 1973
SP  - 149
EP  - 164
VL  - 19
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/IM_1973__19_142192/
ID  - IM_1973__19_142192
ER  -