Interaction of d=2 c=1 Discrete States from String Field Theory
  Starting from string field theory for 2d gravity coupled to c=1 matter we analyze the off-shell tree amplitudes of discrete states. The amplitudes exhibit the pole structure and we use the off-shell calculus to extract the residues and prove that just the residues are constrained by the Ward Identities. The residues generate a simple effective action. 
I.Ya.Aref'eva, P.B.Medvedev and A.P.Zubarev