@article{10_4153_CMB_1995_033_9,
     author = {Phillips, N. Christopher},
     title = {Every {Invertible} {Hilbert} {Space} {Operator} is a {Product} of {Seven} {Positive} {Operators}},
     journal = {Canadian mathematical bulletin},
     pages = {230--236},
     year = {1995},
     volume = {38},
     number = {2},
     doi = {10.4153/CMB-1995-033-9},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1995-033-9/}
}