On superposition of the autoBaecklund transformations for   (2+1)-dimensional integrable systems
  The usual superposition formulas for Baecklund transformations of (2+1)-dimensional integrable systems include quadratures unlike the well known case of (1+1)-dimensional inegrable systems where the fourth solution is found with algebraic operations. In the present paper we show how in the case of (2+1)-dimensional integrable systems one can find an extended formula of nonlinear superposition such that the resulting solution will be found uniquely from the given previous solution with algebraic operations. 
E. T. Ganzha, S. P. Tsarev (Krasnoyarsk State Pedagogical University)