Reduction of the Knizhnik-Zamolodchikov Equation - a Way of Producing   Virasoro Algebra Singular Vectors
  It is shown that the sl(2,C) KZ equation for (half-) integer isospins recovers, up to a gauge transformation, the matrix system for Virasoro algebra singular vectors of Bauer et al. In the case of Kac-Kazhdan spins the general (infinite matrix) KZ system is truncated due to the decoupling of the A^(1)_1 singular vectors. This suggests an algorithm converting Malikov-Feigin-Fuks singular vectors into Virasoro ones. 
A.Ch. Ganchev and V.B. Petkova