An application of the Sakai's theorem to the characterization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="$H^*$"><mml:msup><mml:mi>H</mml:mi><mml:mo>*</mml:mo></mml:msup></mml:math>-algebras
International journal of mathematics and mathematical sciences