@article{GDZPPN002090260, title = {Perturbation of Harmonic Spaces and Construction of Semigroups.}, journal = {Inventiones mathematicae}, volume = {20}, year = {1973}, pages = {149-164}, zbl = {0258.31005}, url = {http://dml.mathdoc.fr/item/GDZPPN002090260} }
Hansen, W. Perturbation of Harmonic Spaces and Construction of Semigroups.. Inventiones mathematicae, Tome 20 (1973) pp. 149-164. http://gdmltest.u-ga.fr/item/GDZPPN002090260/