Integrability of the Wess_Zumino-Witten model as a non-ultralocal theory
  We consider the 2--dimensional Wess--Zumino--Witten (WZW) model in the canonical formalism introduced in a previous paper by two of us. Using an $r$--$s$ matrix approach to non--ultralocal field theories we find the Poisson algebra of monodromy matrices and of conserved quantities with a new, non--dynamical, $r$ matrix. 
S. Rajeev A. Stern and P. Vitale