Meh. Ismail et M. Rahman, LADDER OPERATORS FOR SZEGO POLYNOMIALS AND RELATED BIORTHOGONAL RATIONAL FUNCTIONS, Proceedings of the American Mathematical Society, 124(7), 1996, pp. 2149-2159
We find the raising and lowering operators for orthogonal polynomials
on the unit circle introduced by Szego and for their four parameter ge
neralization to (4) phi(3) biorthogonal rational functions on the unit
circle.