@article{JRAM_1976__0283_0284_151736,
     author = {Richard W. Carey},
     title = {A unitary invariant for pairs of self-adjoint operators.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {294--312},
     publisher = {mathdoc},
     volume = {0283_0284},
     year = {1976},
     zbl = {0348.47013},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1976__0283_0284_151736/}
}