@article{AM2_1991__42_3_137431,
     author = {Dragomir Z. Dokovic},
     title = {Unitary similarity of projectors.},
     journal = {Aequationes mathematicae},
     pages = {220--224},
     year = {1991},
     volume = {42},
     number = {3},
     zbl = {0749.15005},
     url = {http://geodesic.mathdoc.fr/item/AM2_1991__42_3_137431/}
}