Form Factors, deformed Knizhnik-Zamolodchikov equations and finite-gap   integration
  We study the limit of asymptotically free massive integrable models in which the algebra of nonlocal charges turns into affine algebra. The form factors of fields in that limit are described by KZ equations on level 0. We show the limit to be connected with finite-gap integration of classical integrable equations. 
Fedor A. Smirnov