@article{MZ_1979__169_172880,
     author = {Palle E.T. Jorgensen},
     title = {Selfadjoint {Extension} {Operators} {Commuting} with an {Algebra.}},
     journal = {Mathematische Zeitschrift},
     pages = {41--62},
     publisher = {mathdoc},
     volume = {169},
     year = {1979},
     zbl = {0389.47014},
     url = {http://geodesic.mathdoc.fr/item/MZ_1979__169_172880/}
}