Hadronic Matter in the Robertson-Walker Metric and the Early Universe
  In this work, the Friedman equations for hadronic matter in the
Robertson-Walker metric in the early Universe are obtained. We consider the
hadronic phase, formed after the hadronization of the quark-gluon plasma, that
means times from 10^{-6}s to 1s. The set of equations is derived and the
behavior of the system is studied considering one approximate analytical
solution.
