  Experimental and theoretical studies of fluctuations in nucleus-nucleus
interactions at high energies have started to play a major role in
understanding of the concept of strong interactions. The elaborated procedures
have been developed to disentangle different processes happening during
nucleus-nucleus collisions. The fluctuations caused by a variation of the
number of nucleons which participated in a collision are frequently considered
the unwanted one. The methods to eliminate these fluctuations in fixed-target
experiments are reviewed and tested. They can be of key importance in the
following ongoing fixed-target heavy-ion experiments: NA61/SHINE at the CERN
SPS, STAR-FT at the BNL RHIC, BM\@N at JINR Nuclotron, HADES at the GSI SIS18
and in future experiments such as NA60+ at the CERN SPS, CBM at the FAIR
SIS100, JHITS at J-PARC-HI MR.
