@article{AIF_2009__59_2_595_0,
     author = {Cordaro, Paulo D. and Hanges, Nicholas},
     title = {A {New} {Proof} of {Okaji{\textquoteright}s} {Theorem}  for a {Class} of {Sum} of {Squares} {Operators}},
     journal = {Annales de l'Institut Fourier},
     pages = {595--619},
     publisher = {Association des Annales de l{\textquoteright}institut Fourier},
     volume = {59},
     number = {2},
     year = {2009},
     doi = {10.5802/aif.2442},
     mrnumber = {2521430},
     zbl = {1178.35138},
     language = {en},
     url = {https://aif.centre-mersenne.org/articles/10.5802/aif.2442/}
}