@article{10_1017_S2040618500033992,
     author = {Putnam, C. R.},
     title = {On {Differences} of {Unitarily} {Equivalent} {Self-Adjoint} {Operators{\textdagger}}},
     journal = {Glasgow mathematical journal},
     pages = {103--107},
     year = {1960},
     volume = {4},
     number = {3},
     doi = {10.1017/S2040618500033992},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S2040618500033992/}
}