On Lepowsky-Wilson's Z-algebra
  We show that the deformed Virasoro algebra specializes in a certain limit to Lepowsky-Wilson's Z-algebra. This leads to a free field realization of the affine Lie algebra \hat{sl_2} which respects the principal gradation. We discuss some features of this bosonization including the screening current and vertex operators. 
Y. Hara, M. Jimbo, H. Konno, S. Odake and J. Shiraishi