@article{MZ_1992__211_3_174466,
     author = {Tadeusz Dobrowski and Janusz Grabowski},
     title = {Subgroups of {Hilbert} spaces.},
     journal = {Mathematische Zeitschrift},
     pages = {657--670},
     publisher = {mathdoc},
     volume = {211},
     number = {3},
     year = {1992},
     zbl = {0762.46015},
     url = {http://geodesic.mathdoc.fr/item/MZ_1992__211_3_174466/}
}