%0 Journal Article %A Cordaro, Paulo D. %A Hanges, Nicholas %T A New Proof of Okaji’s Theorem for a Class of Sum of Squares Operators %J Annales de l'Institut Fourier %D 2009 %P 595-619 %V 59 %N 2 %I Association des Annales de l’institut Fourier %U https://aif.centre-mersenne.org/articles/10.5802/aif.2442/ %R 10.5802/aif.2442 %G en %F AIF_2009__59_2_595_0