@article{MAN_1969__182_161853,
     author = {M. HASEGAWA},
     title = {On a {Property} of the {Infinitesimal} {Generators} of {Semigroups} of {Linear} {Operators.}},
     journal = {Mathematische Annalen},
     pages = {121--126},
     publisher = {mathdoc},
     volume = {182},
     year = {1969},
     zbl = {0175.43601},
     url = {http://geodesic.mathdoc.fr/item/MAN_1969__182_161853/}
}