  Let $\Omega$ be a bounded smooth domain in $\mathbb{R}^{4}$ such that for
some integer $d\geq1$ its $d$-th singular cohomology group with coefficients in
some field is not zero, then problem
  {\Delta^{2}u-\rho^{4}k(x)e^{u}=0 & \hbox{in}\Omega,
  u=\Delta u=0 & \hbox{on}\partial\Omega,
  has a solution blowing-up, as $\rho\to0$, at $m$ points of $\Omega$, for any
given number $m$.
