Pincus J.D. <br/><br/>
Principal Currnets for a Pair of Unitary Operators. 
Pincus J.D., Zhou Sh. 
 - Providence  Amer. Math. Soc.  1994 
 - 112 p. 
<br/><br/> Memoirs of the Amer. Math. Soc., Vol. 109, N 522 
<br/><br/><label>Dewey Class. No.: </label>MAMS