On the Importance of Isospin Effects for the Interpretation of Nuclear   Collisions
  It is demonstrated that many aspects of nuclear collisions, as for instance the evolution of $\pi^{+}/\pi^{-}$ and $K/\pi$ ratios with $x_F$ and $\sqrt{s}$, are influenced by isospin effects already present in elementary nucleon--nucleon collisions. 
Ondrej Chvala