The critical $A_{n-1}^{(1)}$ chain
  We study the $A_{n-1}^{(1)}$ spin chain at the critical regime $|q|=1$. We give the free boson realizations of the type-I vertex operators and their duals. Using these free boson realizations, we give the integral representations for the correlation functions. 
T.Kojima and S.Yamasita