Multipoint Green's functions in 1+1 dimensional integrable quantum field   theories
  We calculate the multipoint Green functions in 1+1 dimensional integrable quantum field theories. We use the crossing formula for general models and calculate the 3 and 4 point functions taking in to account only the lower nontrivial intermediate states contributions. Then we apply the general results to the examples of the scaling $Z_{2}$ Ising model, sinh-Gordon model and $Z_{3}$ scaling Ising model. We demonstrate this calculations explicitly. The results can be applied to physical phenomena as for example to the Raman scattering. 
H. M. Babujian, M. Karowski and A. M. Tsvelik
hep-th