@article{MM2_1986__54_155111,
     author = {Konrad Schm\"udgen},
     title = {On {Commuting} {Unbounded} {Self-Adjoint} {Operators.} {III.}},
     journal = {Manuscripta mathematica},
     pages = {221--248},
     publisher = {mathdoc},
     volume = {54},
     year = {1986},
     zbl = {0649.47022},
     url = {http://geodesic.mathdoc.fr/item/MM2_1986__54_155111/}
}