Multiple Production of MSSM Neutral Higgs Bosons at High--Energy   $e^+e^-$ Colliders
  The cross sections for the multiple production of the lightest neutral Higgs boson at high--energy $e^+ e^-$ colliders are presented in the framework of the Minimal Supersymmetric extension of the Standard Model (MSSM). We consider production through Higgs--strahlung, associated production of the scalar and the pseudoscalar bosons, and the fusion mechanisms for which we will use the effective longitudinal vector--boson approximation. These cross sections allow one to determine trilinear Higgs couplings $\lambda_{Hhh}$ and $\lambda_{hhh}$, which are theoretically predicted by the Higgs potential. 
A. Djouadi (U. Karlsruhe and DESY), H.E. Haber (U.C. Santa Cruz) and   P.M. Zerwas (DESY)